At least 15 people have been killed and 55 injured in twin suicide car bomb attacks in Baghdad.

The bombs exploded in quick succession near a market in the mainly Shia New Baghdad district, in the east of the city, Iraqi police sources say.

There has been a string of attacks on markets. The worst killed 88 people.

The attacks come despite the arrival last week of the first of more than 21,000 extra US troops intended to bring an end to sectarian violence.

In other violence on Saturday:

· Iraqi police said eight computer firm employees were kidnapped by men in police uniforms in central Baghdad

· The US military said it had killed 14 suspected insurgents during an air strike on a building used as a hideout south of Baquba

· A rocket or mortar landed inside Baghdad's Green Zone near the US Embassy. It is unclear if anyone was injured

Shia targets

Saturday's deadliest attack near a bird market in New Baghdad began when a suicide car bomber exploded his car in a busy street.

A second bomber then triggered an explosion minutes later, targeting those who had come to help victims of the first bomb.

Shop owner Farooq Haitham told Associated Press news agency onlookers had ferried the injured to hospital in civilian cars.

"This area has witnessed many explosions, but what can we do? We want to live, our need for money forces us to come again and work," he said.

The BBC's correspondent in Baghdad, Mike Wooldridge, says that markets of various kinds have been a particular target in recent days, many in predominantly Shia areas.

On Friday, an explosion in Ghazil pet market in the city centre killed 15 and injured 35 others.

An attack on a market in Baghdad's central neighborhood of Bab al-Sharqi on Monday killed 88.

The Iraqi government has pledged to tackle the bloodshed from both sides of the sectarian divide as part of a new security offensive.

However, US President George W Bush's strategy for imposing security in Baghdad and beyond has faced strong opposition from Congress.

The Senate is mulling non-binding resolutions to express its opposition to his plans.

But on Friday, Mr Bush made it clear he will ignore any attempt by Congress to question his decision to bolster troop numbers.

A demonstration in opposition to the troop increase is now under way in Washington.

Thousands have gathered to put pressure on Congress to use its power to withdraw finance for the war in Iraq.

Also on Saturday, Russia said it planned to question the US on its increasing military presence in the Middle East.

Foreign Minister Sergei Lavrov said he would seek an explanation during a visit to Washington next week.

He also said it was his "deep conviction that Iran and Syria should not be isolated and must be involved in the settlement process".

Photo caption

Man with child in Baghdad hospital