"A policeman was shot dead while two policemen and three civilians were injured by stones or batons," he added.

The protest was against the stranglehold that the two principal parties have on the semi-autonomous region. For decades, the Kurdistan Democratic Party (KDP) and the Patriotic Union of Kurdistan (PUK) have lorded over the oil-rich northern territory.

"The gathering began around 3:00 pm (1200 GMT) in the centre of Halabja. but shortly afterwards turned into a confrontation when the police prevented the demonstrators from advancing to the offices of the Directorate of General Security," the official said.

On February 23, a policeman was killed and another wounded during a demonstration in Halabja, east of the city of Sulaimaniyah, which has seen daily demonstrations for a month.

Several thousand demonstrators gathered in Sulaimaniyah on Tuesday, demanding the resignation of the regional government, denouncing official corruption and demanding those behind the killing of three young protesters who died in clashed with KDP security forces last month be brought to justice.