Sulaimaniyah (Iraq) (AFP) - At least 600 people have been arrested since protests began last week against authorities in Iraqi Kurdistan over corruption and the fallout from a failed independence push, lawmakers said Tuesday.

They said hundreds of them were still being held over the unrest, which saw protesters torch offices of political parties in the autonomous region in northern Iraq as anger boiled over at the fallout from an independence referendum.

Five demonstrators were shot dead and dozens wounded by security forces in the town of Rania a week ago.

Out of the 600 or more people detained, up to around 300 protesters are still being held "without any legal basis" in Sulaimaniyah province, said Sarwa Abdul Wahid, a lawmaker with the Goran opposition party.

They "were not brought before a judge and did not see their families or lawyers", she said, alleging mistreatment of the detainees, mostly young Goran supporters.

Another Kurdish lawmaker, Hoshyar Abdallah, said hundreds of people had been arrested.

September's overwhelming vote in favour of breaking away drew stinging reprisals from the central government that have battered Iraqi Kurdistan's already flagging economy and fuelled ire over official graft.

The protests have ebbed in recent days in the face of tight security.

The speaker of the regional parliament, Yusuf Mohammed of Goran, announced his resignation at a news conference on Tuesday, saying he had received death threats without elaborating.

He had been unable to fulfil his duties for the past two years in any case because of political divisions that have paralysed the Kurdish parliament since 2015.

A judge meanwhile ordered the release on bail of Shaswar Abdul Wahid, a former television station head who founded a protest movement, his lawyer said.

He had been arrested a week ago when returning from London.