The Iraqi Government admitted today that its security forces had captured Abu Musab al-Zarqawi, the one-legged Jordanian terror chief whose picture is plastered all over the country, but let him go because nobody recognised him.

Iraq's most-wanted man was arrested in the rebel stronghold of Fallujah last year with a group of other insurgents, but he was released after a "simple interrogation".

The confession was made by Hussain Kamal, the deputy Interior Minister. "He was arrested more than one year ago in Fallujah by Iraqi police," Mr Kamal said. "It seems they did not recognize him, that’s why they released him."

The shadowy Jordanian-born Islamist - who is thought only to have one leg after being injured fighting for the Taleban in Afghanistan - has a $25 million US bounty on his head.

"He is human, he does not have the power of God," Mr Kamal insisted."We will bring him to justice. He got away once, he will not get away the next time."

Al-Zarqawi, 39, is allegedly the mastermind of numerous bombings, armed attacks, hostage murders and other acts of violence in Iraq, and has been sentenced to death in Jordan for the 2002 murder of a US diplomat. US forces blame him for the deaths of at least 700 people in bombing attacks and abductions in Iraq.

The leader of al-Qaeda in Iraq, al-Zarqawi is also believed to have personally murdered Ken Bigley, the British hostage beheaded in September 2004.

US forces in Iraq say they have killed or captured a number of Zarqawi's operatives and have come close to capturing al-Zarqawi himself on several occasions.

"We come close to Zarqawi continuously and at one point in time, in the not too distant future, we are going to get Zarqawi," Major General Rick Lynch, spokesman for the US-led multinational force in Iraq, said last month.

In Jordan, he was sentenced in 1994 to 15 years in prison for membership in an illegal group and arms possession, but later freed under a general amnesty by King Abdullah in May 1999. He has topped the US most-wanted list in Iraq since Saddam Hussein’s downfall in April 2003, and has the same price on his head as Osama bin Laden.

Unlike bin Laden, however, al-Zarqawi has never released a videotaped message and preferrs to remain a shadowy figure. Only grainy identity shots, old images from Afghanistan and more recent photos of a portly, grizzled figure give any clue as to his appearance.

Richard Beeston, Diplomatic Editor of The Times, said from Baghdad that details of al-Zarqawi's capture were sketchy and officials in Falluhjah itself had denied any knowledge of it.

"It's entirely plausible," Beeston said. "It sounds corny but he is a master of disguise - the pictures released by the Americans show him with a beard, without a beard, with or without a dishdash or glasses.

"My impression is that they subsequently caught somebody who told them, 'you had him'."

Born Fadel Nazzal al-Khalayleh in October 1966, al-Zarqawi became a radical after being shocked by the social openness that emerged in conservative Jordan with the arrival of tens of thousands of Palestinians who fled Kuwait after Iraq invaded the Gulf emirate in 1990.

A veteran of the Afghan war against Soviet occupation, a US-backed conflict in the 1980s that drew many Muslim idealists, al-Zarqawi’s encounter with bin Laden took place in 2000 during visits to Pakistan and Afghanistan.

In late 2001, he was wounded in combat and lost a leg after taking up arms against US-led forces fighting to unseat the Taliban.

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