The UK is to step up its operation in Iraq three years after the last combat troops left the country, the Defence Secretary has announced.

Michael Fallon said the move was necessary to challenge the growing threat posed by Islamic State terrorists.

He stressed that the move would not involve putting troops on the ground.

Instead, military personnel will take part in a "limited" training mission for local security forces.

However, he admitted that he could not yet say how many members of the Armed Forces would eventually be involved.

The move was announced just days after the commemorations to mark the departure of the last UK troops from Afghanistan.

On a visit to Iraq to oversee the UK efforts to combat IS extremists, Mr Fallon said: "The Prime Minister's made it very, very clear we are not going to recommit combat troops to Iraq.

"We've been there, we've done that.

"What we are going to do is to help the new government of Iraq and its own army take the fight to IS through the aircraft that we've deployed in the sky, through intelligence gathering and through specialist training."

But Rose Gentle, the mother of 19-year-old ­Fusilier Gordon Gentle who was killed in Iraq in 2004, said she was disappointed that British involvement was growing.

"It's going to bring back a lot of memories for the families, but I think we knew it would happen," she said.

The last combat troops deployed with Operation Telic, as it was called, left Iraq in April 2009, with a small number staying on to train Iraqi forces until 2011.