Iraqi lawmakers Tuesday approved the return of a limited number of British troops to Iraq to help protect the country's southern oil ports — an area where Iraq is lagging in its ability to provide security.

Iraq's parliament approved the security agreement with Britain months after the military contingent was forced to pull out because a United Nations mandate allowing British troops to legally operate in the country was expiring.

Under the agreement in parliament Tuesday, about 100 British troops would return for about a year to provide protection to the oil sites and train Iraqi forces. Iraq's president and two vice presidents still must sign off on the agreement.

The deal limits British military operations in Iraq strictly to naval operations at the southern port of Umm Qasr, said Jabir Khalifa Jabir from the parliament's oil and gas committee.

Britain had about 40,000 troops in Iraq following the 2003 U.S.-led invasion, but withdrew almost all their forces earlier this year. A contingent of about 100 to 150 troops who were training Iraq's new navy remained, but those forces were moved to Kuwait when Iraq's parliament went on summer break without agreeing to allow the British to stay.

U.S. military officials have repeatedly said Iraq has still not purchased the navy ships and patrol planes it badly needs.

Tuesday's pact drew objections and harsh words from Sadrist lawmakers, who walked out of during the vote. The Sadrist group has about 30 legislators in the 275-member parliament. Their leader, anti-U.S. cleric Muqtada al-Sadr, once staged bloody rebellions against U.S.-led troops, and has strongly objected to any remaining foreign troops, including U.S. forces.

"We left parliament when the voting began because we do not believe in this," said Sadrist lawmaker Falah Shanshal. "We wanted our objection recorded."

Meanwhile, Iraqi lawmakers facing a looming deadline resumed talks Tuesday on the election law — a key piece of legislation that may affect the credibility of the country's parliamentary vote in January.

Iraq's electoral commission gave the assembly until Thursday to approve new voting guidelines that would require ballots to list individual candidates rather than just their party blocs.

If the lawmakers miss the deadline, Iraq will revert to voting guidelines used in the 2005 parliamentary elections, in which only party names were listed on the ballots.

Iraq's leading Shiite cleric, Grand Ayatollah Ali al-Sistani, has threatened to boycott the elections if ballots only carry the names of party blocs. He says listing individual names will encourage voter participation.