They retook the Al-Sinek, Al-Shuhada and Al-Ahrar bridges over the River Tigris that link the east bank, where the main protest camps are located, with neighbourhoods on the west bank that are home to government offices and foreign embassies.

Amid volleys of tear gas, security forces chased demonstrators back onto Al-Rasheed Street, one of Baghdad's oldest and most celebrated thoroughfares.

Protesters still occupy part of Al-Jumhuriyah (Republic) Bridge, the southernmost of the capital's bridges and the closest to the main protest camp in Tahrir (Liberation) Square.

Over the past two weeks, demonstrators had spilt over from the square, first taking over part of Al-Jumhuriyah Bridge before creeping north onto the other three.

But the government ordered the security forces to keep them back, as Al-Jumhuriyah Bridge leads into the Green Zone where parliament and the British and US embassies are located.

Al-Sinek Bridge provides access to the embassy of Iran, a target for protesters who accuse Iraq's eastern neighbour of propping a government they regard as irredeemably corrupt.

Al-Ahrar (Free Men) and Al-Shuhada (Martyrs) bridges lead to the prime minister's office and state television headquarters.

Security forces have fired tear gas and both live and rubber bullets to keep the protesters back. They have even fired machine guns.

The sound of tear gas canisters and stun grenades reverberated around central Baghdad nightly over the past week.

Fired at point-blank range, the canisters have pierced protesters' skulls and chests, killing at least 16 of them, according to the United Nations.

Amnesty International said it has found the military-grade tear gas canisters were Serbian- or Iranian-made.

Nearly 300 people have been killed in protest-related violence since demonstrations erupted on October 1 and swiftly spread from Baghdad to cities across the south, according to an AFP toll.

The government has stopped issuing updated tolls.