Hundreds of Islamist protesters have stormed Iraq's parliament building in Baghdad.

They're said to be angry at the failure of politicians to approve a new cabinet.

The demonstrators gained access to the building after they managed to break in to the city's high security Green Zone.

The demonstrators are supporters of extremist Shi'ite Muslim cleric Moqtada al-Sadr.

There were no reports of clashes with security forces. But special forces personnel from Iraq's army were dispatched with armoured vehicles to protect sensitive sites, two security officials were reported as saying. No curfew has been imposed.

UN and Western diplomats in the Green Zone said their compounds were locked down.

Local guards said protesters surged in after security forces pulled back from an external checkpoint in an unsuccessful effort to secure the parliament building.

Local tv broadcast footage from inside the parliament building showing hundreds of protesters dancing, waving Iraqi flags, chanting pro-Sadr slogans and breaking furniture.

Supporters of Sadr have been protesting in Baghdad for weeks, after their leader put pressure on Prime Minister Haideral-Abadi to carry out long-promised reform.