Three rockets slammed into the US embassy in Iraq's capital on Sunday in the first direct hit reported after months of close calls, as thousands kept up anti-government sit-ins across the country.

The attack marked a dangerous escalation in the spree of rocket attacks in recent months that have targeted the embassy or Iraqi military bases where American troops are deployed.

None of the attacks has been claimed but Washington has repeatedly blamed Iran-backed military factions in Iraq.

On Sunday, one rocket hit an embassy cafeteria at dinner time while two others landed nearby, a security source told AFP.

A senior Iraqi official told AFP at least one person was wounded, but it was not immediately clear how serious the injuries were and whether the person was an American national or an Iraqi staff member working at the mission.

The US embassy did not immediately respond to requests for comment.

The attack took place earlier in the day than usual, with AFP reporters hearing the booms on the western bank of the river Tigris at precisely 7:30 pm (1630 GMT).

Iraqi Prime Minister Adel Abdel Mahdi and Speaker of Parliament Mohammed Halbusi both condemned the incident, saying it risked dragging their homeland into war.

Iraq has already been dragged into a worrying tit-for-tat between the United States and Iran over the last month.