Iraq’s prime minister called on anti-government protesters to reopen roads on Sunday after a month of major rallies to demand wide-ranging political change.

Adil Abdul-Mahdi called for markets, factories, schools and universities to reopen after days of protests in the capital and across the mostly Shia south. He said the threat to oil facilities and the closure of roads had cost the country billions of dollars and contributed to price increases that affected everyone.

Tens of thousands of protesters have gathered in Baghdad’s central Tahrir Square and across southern Iraq in recent days, calling for the overhaul of the political system established after the US-led 2003 invasion. Protesters have also taken over a large tower in the square that was abandoned after it was damaged in the war.

Thousands of students have skipped classes to take part in the rallies, blaming the political elite for widespread corruption, high unemployment and poor public services.

Protesters had blocked roads around their main protest site with burning tyres and barbed wire earlier on Sunday. They unfurled a banner at one roadblock reading: “Roads closed by order of the people.” They appeared to be borrowing a tactic from Lebanon, where similar demonstrations have been underway since 17 October.

Iraqi security forces have fired teargas, rubber bullets and live ammunition at the protesters, killing at least 256 people in two waves of demonstrations since early October. Since the protests restarted on 25 October after a brief hiatus, there have been clashes on two bridges leading to the heavily fortified Green Zone, the headquarters of the government and home to several foreign embassies.

Iraq is governed by a sectarian political system that distributes power and high offices among the Shia majority, Sunnis and Kurds. It holds regular elections, but they are dominated by sectarian religious parties, many of which have close ties to Iran.

More than 15 years after the overthrow of Saddam Hussein, power cuts are still common in Baghdad and other cities, the tap water is undrinkable and public infrastructure crumbling. Few Iraqis have seen any benefit from the country’s oil wealth, despite it being an Opec member with the world’s fourth-largest proven reserves.