Baghdad - A bomb that had been confiscated by Iraqi police accidentally exploded in a police station in the city of Diwaniya, early Friday killing three and injuring 20, police and security sources said.

The bomb was one of a number of explosives seized by Iraqi police in different parts of Diwaniya, located about 160 kilometres south of Baghdad.

The device blew up while police were trying to disarm it, a security source told the Voices of Iraq (VOI) news agency.

The accident came as Iraqi security forces are trying to pacify various parts of the country ahead of provincial elections set for Saturday. So far six candidates for the elections have been murdered, three of whom were killed Thursday.

The elections are the first to be held without the supervision of US troops occupying in the country and are seen as a test of Iraq's sectarian reconciliation.

The three candidates killed yesterday included Abbas Farhan al- Azzawi, who along with his brother and a cousin (neither of whom were candidates), was gunned down late Thursday in the restive Diyala city by suspected al-Qaeda militants.

Al-Azzawi was a candidate for Reform and Development, a predominately Sunni Muslim party.

The party is composed of former members of Iraq's security forces along with members of the Awakening Councils, which are Sunni tribe members and former insurgents who collaborated with US forces in fighting the al-Qaeda terrorist network in Iraq.

Although many Sunni Arabs boycotted the 2005 provincial vote, observers believe this year they will present strong political competition to the Shiite Muslims, who form a majority in the war- torn country. (dpa)