BAGHDAD - Striking Iraqis sealed off key bridges and avenues in Baghdad and across the south Sunday, boosting a weeks-long street movement that is demanding a government overhaul.

Sit-ins have become the go-to tactic for rallies that erupted in early October in fury over corruption, a lack of jobs and an out-of-touch political class.

They have resisted efforts by security forces to snuff the gatherings out and on Sunday, thousands came out across the country after activists called for a general strike.

In the southern hotspots of Kut, Najaf and Diwaniyah schools and government offices were shut as swelling crowds hit the streets.

Protesters burned tires to block roads in the oil-rich port city of Basra and outside Nasiriyah, prompting security forces to send reinforcements.

In Hillah, south of Baghdad, students and other activists massed in front of the provincial headquarters.

"We'll keep up our protest and general strike with all Iraqis until we force the government to resign," said Hassaan al-Tufan, a lawyer and activist.

In Baghdad, protesters expanded their sit-in from the main protest camp of Tahrir (Liberation) Square further north to the Al-Ahrar (Free Men) bridge.

Along with Al-Jumhuriyah and Al-Sinek, that brings to three the number of bridges whose eastern approaches are occupied by protesters.

They are highly strategic, linking the eastern bank of the Tigris to the west, where parliament, the premier's office and other key buildings are located.

Along each bridge, security forces stationed behind thick concrete blast walls lob tear gas grenades and shoot live rounds -- even machine gun fire -- to keep protesters back.

Al-Jumhuriyah leads to the Green Zone, the high-security enclave housing the US embassy.

Al-Sinek, which protesters retook on Saturday, leads to the embassy of neighboring Iran, which protesters have criticized for propping up the government they want to bring down.

Iraq's neighbor has faced its own deadly agitation since a hike in petrol prices was announced on Friday in a country already crippled by US sanctions.

Tehran holds immense sway over many of Iraq's political and military actors, but large numbers of protesters have described its influence in recent weeks as an overreach.

On Sunday, hundreds of students skipped class to gather in Tahrir, the beating heart of the protest movement.

"No politics, no parties, this is a student awakening!" read one banner carried by young Iraqis with rucksacks.

"We students are here to help the other protesters, and we won't retreat a single step," said a teenager wearing thick black-framed glasses.

Their push north onto Al-Ahrar bridge was met with heavy gunfire and tear gas, witnesses there told AFP.

A medical source said one protester died of a trauma wound from a tear gas canister, and more than 40 other people were wounded.

Another person was wounded when a rocket hit a commercial street on the eastern bank of the river late Sunday, the security services said in a statement.

More than 330 people have died and around 15,000 people have been wounded since the protests first broke out. -AFP