Arab leaders have begun talks on a UN-backed peace plan for Syria at the first major international summit to be hosted by Iraq in decades.The UN-Arab League plan would see a UN-monitored end to fighting, troops pulled out of opposition areas and access for humanitarian services.
Syria agreed to the initiative on Tuesday but violence has continued.
A number of explosions were heard in central Baghdad as the summit was starting.
Two of the blasts occurred near the Iranian embassy, eyewitnesses said. There are unconfirmed reports that an explosion near the city's secure Green Zone was an IED (improvised explosive device).
There was no immediate official confirmation or explanation of the explosions.
Fewer than half the Arab League's 22 leaders have turned up for the summit, with other states sending envoys.
It is being held in such tight security at the city's former Republican Palace that the venue was not initially disclosed to journalists.
While expectations are not high for the talks, the fact that they are being held in the Iraqi capital at all can be seen as a sign of progress for Iraq, the BBC's Wyre Davies says.
The arrival of the Emir of Kuwait, Sheikh Sabah al-Ahmed al-Jaber al-Sabah, marked the first visit by a leader of that country since Saddam Hussein's invasion in 1990.
ScepticismThe head of the UN, Ban Ki-moon, urged Syria "to put commitments into immediate effect".
"The world is waiting for commitments to be translated into action. The key here is implementation: there is no time to waste," Mr Ban told the summit in Baghdad.
Mr Ban is due to meet key leaders at the summit to discuss how the UN can work with the Arab League to put the plan, brokered by UN envoy Kofi Annan, into action.
Washington has urged countries to maintain pressure on the government of President Bashar al-Assad.
The US state department said it had "not seen the promises that Assad made implemented".
"It's incumbent on all of us to keep the pressure on Assad to meet the commitment that he's made, and that's our intention over the next few days," a spokesperson said.
Syria has said it will not address any initiative from the Arab League, from which it was suspended last year.
The opposition in Syria is sceptical about the terms of Mr Annan's plan, with some saying Mr Assad is merely stalling for time in order to continue his crackdown.
"We are not sure if it's political manoeuvring or a sincere act," said Louay Safi, a member of the opposition Syrian National Council.
"We have no trust in the current regime. ... We have to see that they have stopped killing civilians."
The UN says more than 9,000 people have been killed during the year-long Syrian revolt.
Opposition activists say at least 40 people have been killed since government troops overran the opposition-held town of Saraqeb in the north-west at the weekend.
Corpses littered the streets as homes were burned to the ground and shops pillaged and looted, they said in reports which could not be verified independently.
Security is extremely tight for the Baghdad summit and much of the city has been brought to a standstill for the summit, which is costing an estimated $500m (£314m) to stage.
The Iraqi government is hoping to re-establish itself in the Arab fold after years of violence and sectarian conflict, Wyre Davies reports from Baghdad.
Little progress is expected either on the Syrian front or on wider tensions between Shia and Sunni factions in the region, he notes.
In another development, Russian President Dmitry Medvedev said he was asking fellow emerging economic powers to provide humanitarian aid to the Syrian people.
Speaking in the Indian capital Delhi, he said he had suggested the idea to fellow Brics states Brazil, India, China and South Africa.
In a closing statement, the five states said "lasting solutions" for both Syria and Iran could "only be found through dialogue".