British Prime Minister Gordon Brown says his government has made every effort to secure the release of five British hostages held in Iraq.

The bodies of two of the British men were handed over to authorities on Sunday.

Three other men are thought to remain captive. All five were kidnapped in May 2007 when they were overpowered by armed Shiite militants outside Baghdad's finance ministry.

Some relatives have criticized Britain for doing too little to win their release.

Brown said on Monday that Britain had "left no stone unturned" in efforts to secure the release of the hostages.

He spoke Sunday by telephone with Iraqi Prime Minister Nouri al-Maliki, who pledged new attempts to free the men.