The US-backed Iraqi authorities have urged neighbouring states to tighten their border controls, following a new attack on Iraqi security targets.
At least 30 people were also wounded in the attack
Iraqi Foreign Minister Hoshyar Zebari told his counterparts at a meeting in Kuwait that it was in their own interest to stop foreign infiltrators.
At least 27 people - mostly policemen - died in Saturday's attack in Falluja.
Four attackers were among those killed.
Iraqi officials suspect the insurgents wanted to free foreign fighters.
None of the prisoners released were suspected of involvement in the anti-US insurgency, police said.
Up to 70 men fired mortars, rocket-propelled grenades and machine guns at the mayor's office, the defence corps building and the police station in Falluja, west of Baghdad.
They freed more than 20 prisoners in the co-ordinated assault.
The daylight raid in the flashpoint town was the third major attack on Iraqi defence forces this week, following bombings that left around 100 people dead.
The BBC's Jonny Dymond in Baghdad says this was the most audacious attack so far by militants in post-war Iraq.
In Kuwait, Mr Zebari urged his counterparts from neighbouring states to take "decisive and serious measures to impose tight security on the borders with Iraq".
Before the talks, Mr Zebari told the BBC that he would deliver a simple message that "the stability of Iraq is your stability, the security of Iraq is your security".
US officials believe that foreign fighters are making common cause with local guerrillas to attack US forces and their allies in Iraq.
The meeting was called to assess the security situation in Iraq and US plans for a new political order there.
Ministers from Syria and Saudi Arabia voiced fears that the US plan to restructure Iraq along federal lines before transferring power to a sovereign government at the end of June could undermine the country's unity.
But Mr Zebari - the first Iraqi delegate to attend such a meeting - insisted that "the Iraqi people are committed to national unity".
The foreign ministers of Jordan, Iran, Turkey, Kuwait, Egypt and Bahrain are also attending the meeting.
A final communique is expected to be released later on Sunday expressing support for the 1 July transfer of power and condemning attacks on innocent people in Iraq, the Associated Press reports.
Iraqi Shia leader Ayatollah Ali al-Sistani is spearheading demands for early elections - but UN envoy Lakhdar Brahimi played down any prospect of them as he ended a visit to Iraq on Friday.
POLICE STATION ATTACKS
14 February 2004: At least 22 killed in gun battle outside Falluja station
10 February: At least 45 die in blast in Iskandariya
31 January: Nine killed in blast outside Mosul station
14 December 2003: Car bomb in Khalidiya kills 17
22 November: At least 18 die in twin bombings in Baquba and Khan Bani Saad
In the Falluja assault the insurgents stormed a police station, and more than 20 prisoners were freed as the gunmen went from room to room, shooting and lobbing grenades.
At least 30 people were reported to have been injured.
The BBC's Barbara Plett says there was no sign of American forces in the town, which lies in an area known as the so-called Sunni Triangle - the heartland of the guerrilla campaign against the US-led occupation of Iraq.
The latest attack adds to fears that the Iraqi police cannot protect themselves, let alone anyone else, our correspondent says.
The same security compound in Falluja was attacked two days earlier during a visit by the top US commander in the Middle East, Gen John Abizaid. He escaped unharmed.