An Iranian diplomat has been kidnapped by gunmen in the Iraqi capital, Baghdad, Tehran has confirmed.

Jalal Sharafi, the embassy's second secretary, was abducted from his car on Sunday in central Karrada district by men wearing Iraqi army uniforms.

Iran condemned the kidnapping and said it held the US responsible for his life. A US military spokesman said no US or Iraqi troops were involved.

The news comes amid US-Iranian tension over Iranian activities in Iraq.

In late December the US arrested a number of Iranians in Iraq, prompting Iran to issue a formal protest to the US.

The US has denied any involvement in the latest incident, but in recent weeks it has been expressing increasing concern about alleged Iranian support for militant activity in Iraq.

Correspondents say the stand-off over Iran's nuclear programme is adding to the tension.

Identification puzzle

Iranian foreign ministry spokesman Mohammad Ali Hosseini told the Isna news agency that Mr Sharafi had been kidnapped by a group linked to Iraq's defence ministry "which works under the supervision of American forces".

"The Islamic Republic of Iran holds the American forces in Iraq responsible for the life and safety of the Iranian diplomat," he said.

Iraqi officials earlier said the gunmen were wearing uniforms of the Iraqi 36th Commando Battalion - a special Iraqi unit under US direction.

US military spokesman in Baghdad, Lt Col Christopher Garver, could not confirm the diplomat's abduction.

However, he said: "We've checked with our units and it was not a [multinational forces - Iraq] unit that participated in that event."

Mr Sharafi was reportedly kidnapped outside the Baghdad branch of the Iranian state-owned Bank Melli.

But the details of the abduction are still confused.

Kidnapping 'common'

An Iraqi government official told Associated Press news agency there had been a gun battle and a chase after the kidnapping but the car carrying the diplomat escaped.

Some men were captured but the New York Times quoted Iraqi officials as saying they had legitimate defence ministry identification.

An official told the paper the men may have kept the identification after being dismissed. It is not thought they are still being held.

The BBC's Mike Wooldridge, in Baghdad, says the fact that the kidnappers were wearing uniforms can mean anything in Baghdad.

Kidnapping is common - often criminal rather than political - and frequently carried out by people in some kind of official uniform, he says.

But against the background of the ongoing disagreements between the US and Iran, this is quickly becoming another source of diplomatic tension, our correspondent adds.