By Peter Graff

BAGHDAD, Aug 2 (Reuters) - A suicide bomber drove a car bomb into an Iraqi police station on Thursday, killing 13 people, while politicians prepared for a summit to restore a coalition government after the main Sunni group quit.

The attack followed a day of major bombings in Baghdad, in which 70 people were killed.

A police source said the bomber struck recruits lined up to join the police force in the town of Hibhib, north of Baghdad. The dead included six policemen and seven civilians. Fifteen people were wounded.

Leaders of Iraq's main groups are due to meet in coming days to try to stitch back their coalition, which was set up last year and has so far failed in its aim of reducing violence or agreeing on laws aimed at reconciliation.

The office of Prime Minister Nuri al-Maliki, a Shi'ite, said he would remain in permanent contact with the Sunni Accordance Front, despite its decision to pull its six ministers out of the government on Wednesday.

The Front said it was quitting Maliki's coalition because he had failed to meet its demands, including giving the Sunni bloc a greater share in security matters.

Another large Shi'ite faction, that of cleric Moqtada al-Sadr, quit the government in April.

Thursday's attack took place in Diyala province, the area north of the capital which has been a focus of a U.S. offensive over the past two months after Washington dispatched extra troops to Iraq to help stabilise the country.

Washington says the area has seen an influx of al Qaeda militants driven out of Baghdad and western Anbar province as a result of the U.S. offensive and a revolt against the militants by local tribes.

Further north, more than 1,000 Iraqi troops launched a crackdown on militants in Samarra, where an attack on a Shi'ite shrine last year triggered sectarian fighting across Iraq. The mosque was attacked again in June.

The Iraqi forces closed streets and imposed a curfew. The U.S. military said the goal of the Iraqi operation was to stabilise the city so the shrine could be rebuilt.

Washington has seen the number of its troops killed in Iraq fall over the past month after the deadliest three-month period of the war. Commanders say the figures show their new strategy is working.

But figures compiled by the ministries of health and interior show the number of civilians killed in July rose by a third to 1,653, after a sharp drop in June.

AlertNet news is provided by