A British member of al-Qaeda has claimed he only agreed to carry out a suicide bombing at Heathrow as a way of escaping from a terror training camp in Yemen where he was suffering from scabies.

Minh Quang Pham, a British citizen born in Vietnam, spent six months in Yemen in 2011 training with al-Qaeda in the Arabian Peninsula (AQAP), one of the deadliest branches of the terror network.

He returned to Britain in July 2011 after allegedly being tasked by Anwar al-Awlaki to build a bomb and and ultimately blow himself up in the arrivals section of Heathrow airport.

The 33-year-old was arrested by British police and extradited to New York where he pleaded guilty in January to three terrorism charges.

Ahead of his sentencing Pham wrote his US judge a 13-page handwritten letter in which he said he was "very naive" when he joined the terror group and insisted he had no intention of actually carrying out the Heathrow attack.

Instead, he said he accepted the mission because it would let him leave Yemen and offer some relief from chronic scabies he was suffering at a desert training camp. "I only wanted to leave Yemen and had to accept a foreign operation," he wrote.