LONDON (AFP) - The British government was under pressure on Monday to explain how a Somali-born terror suspect escaped surveillance by putting on a burqa during a visit to a mosque.

Mohammed Ahmed Mohamed, 27, who was subject to an order restricting his movements, entered a mosque in London on Friday wearing Western-style clothes, but CCTV images showed him leaving disguised as a woman, with his face and body fully covered.

He is understood to have received training and fought overseas for the Somalia-based Al-Shebab, the Al-Qaeda-linked militants who launched the attack on a Nairobi shopping mall in September in which at least 67 people were killed.

Home Secretary Theresa May was due to make a statement to Parliament later on Monday.

Mohamed is under a Terrorism Prevention and Investigation Measures (Tpim) notice, which was imposed primarily to prevent overseas travel.

He is the second person to breach a Tpim since they were introduced to replace control orders in early 2012. They allow suspects to live in public but under stringent restrictions.

Another suspect, Ibrahim Magag, tore off his electronic tag and vanished in a taxi last December. He has not been seen since.

Ms Yvette Cooper, home affairs spokesman for the main opposition Labour party, described the situation as "extremely serious" and demanded answers from the government on how Mohamed was able to abscond.

"The home secretary also needs to provide information about the decisions made over Mohammed Ahmed Mohamed's Tpim, how he was able to abscond and what the risks to the public are," she said.

Police say Mohamed is "not considered at this time to represent a direct threat to the public".

It is believed he attended a training camp in 2008 and is understood to have helped people travel to Britain from Somalia to allow them to engage in terror-related activity.

He is also believed to have procured weapons for terror use.