Once again the capital's iconic Tahrir Square began filling early in the day, as protesters voiced their opposition to names tipped for prime minister in a ruling system they view as inept and ridden with corruption.

Portraits of the candidates, crossed out in red, adorn a growing number of buildings and tents in the protest area.

And once again the main avenues and roads in cities in the south of the country were blocked, as well as entrances to schools, universities and government buildings.

In Tahrir Square and rallying points in the country's south, protesters erected Christmas trees to commemorate the more than 400 "martyrs" of their "October Revolution".

After dwindling in recent weeks following a string of killings of protesters, the civil disobedience campaign has rediscovered its vigour as political parties wrangle over a replacement for outgoing premier Adel Abdel Mahdi.

He quit in November in the face of massive protests against corruption and unemployment, and negotiations to fill his post have remained deadlocked since the latest in a series of deadlines expired at midnight on Sunday.

While a pro-Iran camp has tried to impose a candidate, Iraqi President Barham Saleh has reportedly put up resistance.

For Iraqis protesting since October 1, the system installed by the United States after it led a military coalition to overthrow dictator Saddam Hussein in 2003 has become overly beholden to neighbouring Iran and is beyond reform.

- 'New candidate every hour' -

Protesters say a long-promised economic revival never arrived in OPEC's number two oil producer, with more than half of all crude revenues syphoned off by crooked politicians and their cronies.

Rallies have continued despite a campaign of intimidation that has included targeted killings and abductions of activists, which the United Nations blames on militias.

Politicians have been unable to reach an agreement on who will be the next prime minister, and on Monday parliament did not meet as it failed to reach quorum.

The talks have already overshot a constitutional timeline, with new negotiations due on Tuesday in the face of intransigence by pro-Iranian parties.

"Every hour they come up with a new candidate, but we want someone independent," said one young demonstrator, standing in front of burning tyres on a road into southern Basra.

"We're ready to continue the general strike, a day, two days, three days... even a hundred years if that's what it takes," he added, his face covered by a scarf to keep out the acrid smoke.

- 'Sacrifices' -

Officials say Iran wants to install Qusay al-Suhail, who served as higher education minister in Abdel Mahdi's government.

But parliament speaker Mohammed al-Halbusi announced he had dropped his support for Suhail after a source in the presidency said Saleh had vetoed the proposed appointment.

Instead Halbusi, a Sunni, has urged his pro-Iran allies to come forward with another name.

But as soon as the name of Basra governor Assaad al-Aidani began circulating, demonstrators hit the streets in his oil-rich southern province, blocking roads to the vital ports, an AFP correspondent said.

Roads to southern cities Nasiriyah, Diwaniyah and Hilla were also cut as well as those to Kut and the holy Shiite shrine city of Najaf.

Strikers also closed down schools and stopped government officials reaching work.

After "all the sacrifices", with close to 460 dead since the start of the demonstrations in early October and 25,000 wounded, the protesters say they will not return home until their demands are met.

They are calling for a new constitution, a new electoral law and a complete overhaul of the political system, in a country with crippling unemployment, especially among the youth, who make up more than half the population.

On Tuesday, parliament voted to reform the electoral law, establishing a first-past-the-post system to replace the complex mix of proportional representation and list voting.

Constituencies are also set to be redrawn, but parliament has yet to specify how.

Analysts warn that such a redrawing would favour major parties as well as local and tribal dignitaries over the independent candidates and technocrats protesters want to see in power.