Security has been increased in key areas including Baghdad's Tahrir Square -- the epicentre of the massive demonstrations last year -- and where new concrete barriers have erected.

Some activists say they have been camping out since then in tents around the square, where posters have been erected mourning some of the estimated 600 protesters killed when security forces cracked down.

Protesters have already held demonstrations earlier this month, but demonstrators maintain the new rallies are expected to be significant.

Kazem, a protester who said he has camped at Tahrir Square for an entire year, said that while some wanted peaceful protests, he feared others might inflame the situation.

"We fear on Sunday that some want to escalate the situation in vengeance for our martyrs," he said. "It's very tense."

Protesters on Friday formed an "October Front" political party, made up of a coalition of "21 committees representing demonstrators", and calling for "peaceful protests on Sunday".

Demonstrators had been debating for months whether to field candidates in parliamentary elections slated for June 2021, which were brought forward partly in response to protesters' demands.

Tahrir Square is separated by just a bridge from the fortified Green Zone, the site of parliament, government offices and the US embassy.

Pro-Iran factions have also kept up belligerent rhetoric accusing protesters of being "agents" of the US "occupier".