The Taliban has launched a spring offensive in Afghanistan after carrying out co-ordinated attacks across the capital Kabul targeting the British and other embassies, the heavily guarded palace compound of President Hamid Karzai, the country's parliament and Nato's HQ.

The assault, one of the most serious on the capital since the Taliban was removed from power in 2001, highlighted the ability of militants to strike the heavily guarded diplomatic zone even after more than 10 years of war.

Taliban spokesman Zabihullah Mujahid said the assaults were in retaliation for the burning of copies of the Koran at a Nato base, the killing of 17 Afghan civilians for which a US soldier has been charged as well as for videos apparently showing US Marines urinating on dead Taliban.

The main targets were the British and German embassies and the headquarters of Afghanistan's Nato-led force.

Afghan security forces, who are responsible for the safety of the capital, scrambled to reinforce areas around the so-called green diplomatic quarter.

Attackers fired a rocket-propelled grenade that landed just outside the front gate of a house used by British diplomats in the city centre, a witness said.

British embassy sources said staff were in a lockdown. Two rockets hit a British Embassy guard tower near the Reuters office in the city. There were no reports of casualties.

Several Afghan members of parliament joined security forces repelling attackers from a roof near the parliament.

The co-ordinated attack is bound to intensify worry in the run-up to the planned withdrawal of foreign combat troops by the end of 2014.

Large explosions rattled the diplomatic sector. Billows of black smoke rose from embassies while rocket-propelled grenades whizzed overhead. Heavy gunfire could be heard from many directions as Afghan security forces tried to repel Taliban guerrillas. The Taliban said their fighters were positioned on the rooftop of a tall building in the heart of the capital.

The Taliban also launched assaults in at least two provinces, a spokesman for the insurgents said.

The Interior Ministry said initial intelligence on the wave of attacks across the country pointed to involvement of the Haqqani network, allied with the Taliban and one the most deadly groups in Afghanistan.

If the Haqqanis were involved, that is likely to damage already strained ties between strategic allies the United States and Pakistan.

The US has repeatedly urged the Pakistani military to go after the Haqqani network, which is believed to be based in Pakistan's North Waziristan region on the Afghan border.

"It's too early to say, but the initial findings show the Haqqanis were involved," Afghan Interior Ministry spokesman Sediq Sediqqi said.

The ministry said 17 insurgents, died in the encounters across the country and two were captured.

l Taliban militants attacked a prison in north-west Pakistan yesterday, freeing at least 380 prisoners including at least 20 insurgents described by police as "very dangerous".

The raid by more than 100 fighters was a dramatic display of the strength of the uprising gripping the country. The fighters, armed with automatic weapons and rocket-propelled grenades, attacked the prison before dawn in the city of Bannu in Khyber Pakhtunkhwa.