Iraqi lawmakers linked to populist cleric Moqtada al-Sadr began an indefinite sit-in on Saturday night at parliament headquarters, two MPs told AFP, amid widespread anti-government protests.

A second wave of demonstrations demanding an end to corruption and an overhaul of the political system have rocked the capital Baghdad and the south since late Thursday.

Sadr has already demanded the current government resign, but on Saturday members of his Saeroon bloc -- parliament's largest with 54 MPs -- said they would escalate.

"We are on our way now to parliament for the sit-in, until the enactment of all reforms the Iraqi people are demanding," said MP Badr al-Zayadi.

Saeroon lawmakers were in touch with others to persuade them to join the move, he added.

Zayadi told AFP the bloc had sent an "official request" to Iraqi President Barham Saleh who, according to Iraq's constitution, could then ask parliament to withdraw confidence from the premier.

MP Raed Fahmy, a member of Iraq's Communist Party who is allied to Sadr, confirmed the sit-in.

"We have joined the opposition and we demand the government resign," Fahmy told AFP.

Protests first erupted in Iraq on October 1, over unemployment, poor services and perceived government graft.

More than 150 people died in the initial six-day wave of protests, and another 63 have lost their lives since the rallies resumed this week.

Sadr has called for early elections under the supervision of the United Nations.

But he himself was effectively kingmaker of the current government, after his bloc secured 54 seats in the May 2018 legislative elections.