Iraq’s most infamous Shia death squad commander was accused yesterday of masterminding the kidnapping of five British citizens who have not been heard from since their abduction in Baghdad three months ago.

Hoshyar Zebari, Iraq’s Foreign Minister, told The Times that a group led by Abu Dera, a legendary figure with strong Iranian connections who is renowned for his brutality, was behind the abduction of the five Britons from the Iraqi Finance Ministry on May 29.

Mr Zebari said there was a striking similiarity between their abduction and that of Iraq’s Deputy Oil Minister by Abu Dera’s supporters on August 14. In both instances well-organised forces broke into heavily protected compounds.

The minister and five colleagues were seized by gunmen dressed in security force uniforms who forced their way into the offices of Iraq’s crude oil marketing agency. The Britons were seized by armed men dressed as Iraqi policemen who broke into the Finance Ministry. “I believe the same group who did this did the Ministry of Finance [raid],” Mr Zebari said in an interview in which he also cautioned of “catastrophic consequences” if Britain and America prematurely withdraw from Iraq.

Abdel Jabber al-Wagaa, the Deputy Oil Minister, and his colleagues were released unharmed on Tuesday after what Mr Zebari described as “tough” negotiations with the kidnappers. These talks enabled the Iraqi authorities to establish who the kidnappers were. However, Mr Zebari said he was unaware of any contact with the kidnappers of the Britons – a computer consultant and four security guards – and could not say for certain that they were still alive. “People say that since there’s not been any announcements or videos they may have been killed, but I really don’t know,” he said.

Britain has consistently refused to discuss its efforts to rescue the hostages, or even to name them, and an embassy spokeswoman in Baghdad declined to comment on Abu Dera’s alleged involvement yesterday.

The Foreign and Commonwealth Office is in contact with the families of the five hostages and has advised them all not to speak publicly.

In a separate development yesterday the rebel Shia cleric Moqtada al-Sadr ordered his al-Mahdi Army to suspend all armed activities for six months while it restructured itself.

The al-Mahdi Army has been accused of the widespread killing of Sunni civilians as well as numerous attacks on US and British forces. In April the Pentagon labelled it the biggest threat to stability in Iraq. On Tuesday its gunmen fought a running battle with police allied to the rival Badr Brigade in the Shia city of Kerbala, killing 52 people and forcing hundreds of thousands of pilgrims to abandon an important religious festival.

But US and Iraqi officials were unsure that the announcement would lead to a reduction in violence. Some experts believe that Moqtada simply wants to distance himself from what happened in Karbala, and his authority is no longer absolute. The al-Mahdi Army is said to have splintered in recent months, with breakaway factions backed by Iran being blamed for some of the worst violence. Abu Dera is believed to lead one of those.

He is an elusive figure who is spoken of with awe in the Shia slums of Sadr City, where he was raised.

After the US invasion of 2003 he is thought to have been a leading member of the al-Mahdi Army and to have led attacks on American troops. And when Sunni extremists bombed the Shia shrine in Samarra in 2006 he is said to have led the Shia death squads that killed thousands of innocent Sunnis in revenge. Locals say the Iraqi police allowed him free passage.

Stories of his barbarity are legion. A profile published by the Jamestown Foundation reports that he once commandeered several ambulances, drove them into a Sunni neighbourhood and announced on loudspeakers that Shias were slaughtering Sunnis. The young Sunnis who rushed to help were killed.

He allegedly offers his victims the choice of being executed through suffocation, shooting or being smashed to death with cinder blocks. There is a video recording of a man believed to be Abu Dera kidnapping Saddam Hussein’s lawyer Khamis al-Obeidi, parading him through the streets of Sadr City, and then shooting him three times in the head.

Abu Dera, whose real name is Ismail al-Zerjawi, is thought to be in his late thirties, married with two sons. His daring raids into Sunni communities have made him a hero to many poor young Shias. To others he is known as the “Shiite Zarqawi” – a reference to Abu Musab al-Zarqawi, the former leader in al-Qaeda in Iraq who exhorted Sunnis to kill Shias.

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