An explosion has hit a cafeteria at the Iraqi parliament, killing at least eight people, at least two of them MPs, the US military has said.
The explosion killed at least eight people, the US said
Police said they believed a suicide bomber was involved. Twenty-three people were injured in the attack.
The cafe, in Baghdad's highly fortified Green Zone, is for MPs and their staff, some of whom were having lunch there.
Earlier, a bomb on a bridge in Baghdad killed at least eight people and sent several cars into the River Tigris.
The two attacks are major blows to the much-trumpeted Baghdad security surge now in its third month, the BBC's Jim Muir in Baghdad says.
The convention centre where parliament meets is one of the most heavily guarded buildings in the country, he says.
There are sniffer dogs, and all the other usual precautions are taken. Sometimes several searches are made within the space of just a few metres.
Iraqi Prime Minister Nouri Maliki said the attack was a "criminal cowardly act" and said the violence would not weaken MPs' resolve.
US President George W Bush said he stood with the Iraqi government.
"I strongly condemn the action. It reminds us, though, that there is an enemy willing to bomb innocent people and a symbol of democracy," he said.
Secretary of State Condoleezza Rice said the attack did not mean the security operation had failed.
"We've said there are going to be good days and bad days concerning the security plan but the commanders are carrying out their responsibilities and working to try to make the population more secure," she said.
The bomb went off 10 minutes after the parliament had adjourned for lunch.
One theory suggests it may have been smuggled in by an MP's bodyguard. Reports say two unexploded suicide vests were found later and destroyed.
The bomb exploded in the cafeteria on the first floor where the deputies and other staff were taking their break.
US-funded Al-Hurra TV, which was interviewing MPs at the time, showed politicians ducking under the force of the blast and security officials picking up an injured victim as the room filled with smoke.
MP Mohammed Hassan Awad from the National Dialogue bloc (a Sunni group not part of the government) and at least one other MP were killed.
The bomb exploded 10 minutes into the lunch break
"The canteen was just filling up... the session was just ending and all of a sudden there was just this huge explosion," MP Haydar Abbadi told the BBC.
"The building of course was full of smoke, full of dust, for a few minutes we couldn't see anything, we couldn't see around us."
Despite the tight security it was possible for people without security clearance to get in without being searched, he added.
This is the first time a bomb has gone off inside the building although it has been shaken by several mortar attacks in the past.
The security drive has brought down the rate of sectarian murders, but it has not stopped the bomb attacks.
The bombing of the Sarafiya bridge, one of the main arterial bridges in Baghdad, had been condemned by the speaker of parliament a short time before the explosion in his own building.
The bridge, one of the main links across the Tigris River, was partially demolished by a huge truck bomb.