A nuclear power plant and university in Belgium have been evacuated following the terrorist attacks in Brussels.

Belgian media reported that the Tihange power plant had been evacuated.

The University of Libre de Bruzelles also tweeted that it had been evacuated as a precaution.

The tweet said: "In light of the latest information we have received, we are obliged to evacuate the campuses."

The news comes as Belgian media reported that police had found an unexploded bomb belt in Brussels airport.

ISIS has admitted carrying out the Brussels terrorist attacks which has claimed the lives of at least thirty four people and injured nearly 200. 

Public broadcaster VRT said at least 14 people were killed in two explosions at Zaventem airport this morning.

A second explosion at Maalbeek station, which is close to the EU institution in the centre of the Belgian capital, killed twenty people and injuring 100.

Police in Belgium have confirmed that the three explosions in Brussels were suicide attacks.

The University Hospital Gasthuisberg in Leuven, which treated victims of the terror attacks, said that nail bombs had been used in the attacks.

A spokesperson for the hospital told the media: "The bomb contained nails to create more victims.

"Some victims have nails in their bodies."

All flights to and from Brussels have now been cancelled or diverted.

Belgian prime minister Charles Michel said "what we feared has happened, we were hit by blind attacks".

EU staff were told to stay at home following the explosions at Maelbeek metro station.

Kristalina Georgieva, the European Commissioner for Budget and Human Resources, tweeted: "Following situation in Brussels. EU institutions working together to ensure security of staff & premises. Please stay home or inside buildings."

On the Metro, traveller Evan Lamos tweeted a picture of passengers climbing from his train into the tunnel, saying: "We are being evacuated from the back of the Metro, between Schuman and Maelbeek.

"Smoke in the tunnel as we evacuate."

The Belgium Transport Authority confirmed that all metro stations in Brussels have been closed.

Eurostar has also suspended all of its trains to and from Brussels.

A spokeswoman for the cross-Channel train operator said that services from London to Brussels are terminating in the French city of Lille.

Boris Johnson today said "there may be one UK casualty" in the Brussels explosions.

Ian Duncan MEP has confirmed that a group of students from St Andrews University who were visiting the European Parliament are safe.

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David Cameron chaired a COBRA meeting this morning following the attacks.

Security has been increased at London Gatwick in the wake of the attacks in Belgium.

An airport spokesman said the safety of passengers and staff was the "absolute priority".

He added: "As a result of the terrible incidents in Brussels we have increased our security presence and patrols around the airport."

Heathrow issued a statement which read: "In the light of events in Brussels airport we are working with the police at Heathrow who are providing a high visibility presence."

The coordinated attacks came as the Belgian capital was on a high level of alert following the arrest of Paris atrocity suspect Salah Abdeslam in the city last week.

The first news of the attack came when the airport was rocked by a double blast.

There were unconfirmed reports of shots being fired and shouting in Arabic.

The explosion was close to the American Airlines desk.

Jef Versele, 40, from Ghent, Belgium, was at the airport when he heard the two explosions.

"I was on my way to check in and two bombs went off - two explosions," he said.

"I didn't see anything. Everything was coming down. Glassware. It was chaos it was unbelievable. It was the worst thing."

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He added: "People were running away, there were lots of people on the ground. A lot of people are injured."

Mr Versele was two or three storeys above the source of the explosion but he said many people around him were hurt.

"The bomb was coming from downstairs. It was going up through the roof. It was big.

"About 15 windows were just blown out from the entrance hall", he added.

Belgium's interior minister said the nation's terror threat has been raised to highest level.

Images on social media showed shattered windows and smoke rising from an airport building.

Video footage shot from an airport car park showed people fleeing in terror.

Footage from inside the building showed a scene of devastation with ceiling tiles strewn across the floor and suitcases abandoned.

Airport spokeswoman Anke Fransen said: "There were two blasts in the departure hall. The first aid team are in place for help."

Passengers were led onto the tarmac and travellers were urged to stay away from the airport.

Sky News Middle East correspondent Alex Rossi, who was at the airport en route for Tel Aviv, told the channel: "I could feel the buildings move."

According to reports the incident centred on an American Airlines desk in a departure hall.

Mr Rossi told Sky News people were "dazed and shocked".

"The word is definitely two explosions.

"The thinking here by everybody is that it is some kind of terrorist attack although that hasn't been verified by anyone here at the airport.

"No word too of casualties. Don't know how the explosion took place, the method if you like. But it certainly seems Brussels airport has been targeted in a terrorist attack.

"We are all being moved out of the airport now towards the emergency exit. There is a great deal of confusion here. Certainly there are a number of very upset, as you might imagine, very frightened people."

He added: "There are fears that there might be other attackers."

Mr Rossi, who had checked his luggage through the main baggage area and was at a departure gate, said he thought he was "fairly close" to the explosions but he could not be sure.

He told Sky News as he was being ushered out of the airport along with other passengers: "We felt the walls of the building rock. Dust came down from the ceiling.

"I think it was a very big explosion - hardly surprising the windows are blown out.

"I would expect if there were people around when those explosions happened - we heard two explosions - there will be a number of casualties."

Abdeslam, suspected as a planner in the attacks that killed 130 people in Paris, was arrested on Friday after a four-month manhunt, in the same neighbourhood in Brussels where he grew up.

But the Belgian authorities fear he had accomplices while on the run who are still at large and could pose a threat.

Belgian prosecutor Frederic Van Leeuw told reporters at a news conference in Brussels on Monday: "(It's clear) we have a general threat."

Abdeslam, 26, a French citizen who grew up in Brussels' Molenbeek neighbourhood, slipped through police fingers on several occasions, including the day after the attacks.

He was interviewed three times on Saturday, the day after his capture - once by prosecutors and twice by an investigating judge - and "wasn't in great shape" because he had been shot in the leg by police during his capture, Mr Van Leeuw said.

Belgian prosecutors appealed to the public on Monday for information about a man who allegedly travelled to Hungary last year with Abdeslam.

Najim Laachraoui, 24, is said to have travelled to Syria in February 2013. He was checked by guards at the Austria-Hungary border while driving in a Mercedes with Abdeslam and one other person.

Laachraoui is said to have rented a house under the name of Soufiane Kayal in the Belgian town of Auvelais that was allegedly used as a safe house. Prosecutors said traces of his DNA were found there.

Abdeslam has a court hearing on Wednesday. France has requested his extradition but Abdeslam's lawyer says his client will fight the request.