It may not be the smoking gun that Labour needs to topple Boris Johnson’s administration, but a spot of pilfering from Saddam Hussein’s former regime has come back to haunt the newly elected Mayor of London.

Mr Johnson poured scorn today on a “ludicrous” police investigation which has forced him to hand over a cigar case belonging to Iraq’s former deputy prime minister Tariq Aziz.

Jokingly likening his actions to war crimes, Mr Johnson picked up the souvenir from Mr Aziz’s bombed-out home while visiting Iraq as a journalist in 2003, a few days after the fall of Baghdad.

Scotland Yard has launched an investigation and today confirmed that the red leather case will be held “while further enquiries are made”.

Mr Johnson wrote today: “The poor police have no choice but to investigate this ludicrous affair, and in the interim I am told I must hand the cigar case into police custody - or else be led in manacles from City Hall.

“I briefly toyed with making a fuss, and pointing out how utterly selfish and stupid it was of Labour to waste police time on this kind of thing.”

The episode of the cigar case began during the election campaign. As Mr Johnson has never made any secret of his acquisition, his campaign team accused his opponents of dirty tricks in having the issue referred to police.

Under the Iraq (UN Sanctions) Order 2003, anyone possessing Iraqi cultural property must give it to the police.

Failing to do so is considered an offence, unless the person can prove they were unaware that the property was illegally removed from the country.

Mr Johnson deposited the case into custody yesterday afternoon, following instructions from the police.

He said the circumstances were "so morally ambiguous that I cannot quite think of it as theft".

The mayor claims that he has since received a letter from Mr Aziz, the English-speaking minister who was the face of the Saddam Hussein’s regime, lawyers offering the case as a gift.

However he noted there was one thing to be grateful for from the episode: “It seems that a Western politician is finally going to pay the price for his involvement in the Iraq war,” he wrote in his Daily Telegraph column.

However he asked why other politicians, such as Tony Blair, had not been brought to justice.

"I am informed by my friends in the Metropolitan Police that I am shortly to become the one and only Western politician to be brought to justice for crimes committed in Iraq."

A police spokesman said: "The Met works very closely with a number of countries, including Iraq, to recover items that are considered culturally significant.

"In order to establish the origin and potential significance of the item, such items must be submitted to police custody for further examination."

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