At least 32 people were killed and 71 wounded in twin blasts which rocked Baghdad, security officials said on Friday, more than tripling a previously-announced death toll.

A defence ministry official put the toll from Thursday night's twin roadside bomb attacks in Baghdad's Urr neighbourhood at 32 dead and 71 wounded while an interior ministry official said 36 were killed and 78 wounded.

Both spoke on condition of anonymity.

Officials had given initial tolls of at least 10 dead and 32 wounded.

They said one bomb exploded at around 7:00 pm (1600 GMT) on Thursday followed by a second after security forces and crowds gathered at the scene.

The revised death toll marks the highest since August 15, when twin bombings in the southern city of Kut, blamed on Al-Qaeda, killed 40 people.

The attacks come amid concerns that violence may increase after US forces leave Iraq by the end of the year, and are the deadliest since that decision was announced by US President Barack Obama on October 21.

The US had engaged in protracted and ultimately failed negotiations with Iraq about a post-2011 US military training mission here.

The issue of immunity from prosecution for US trainers was the main sticking point, with Washington insisting its troops be given immunity, while Baghdad said that was not necessary.

The roughly 39,000 US soldiers still in Iraq are now in the process of drawing down, after a nearly nine-year campaign that has left thousands of American soldiers and tens of thousands of Iraqi dead, and costs billions of dollars.