DOZENS of attacks across Iraq, including a brazen car bombing on the way to Baghdad airport, have killed 50 people, just days before the country's first elections since US troops withdrew.

The violence, which mostly struck during Monday morning rush hour amid tightened security ahead of the polls, also wounded nearly 300 people and raises further questions about the credibility of the April 20 vote, seen as a key test of Iraq's stability and its security forces' capabilities.

A total of 14 election hopefuls have already been murdered and just 12 of the country's 18 provinces will be taking part in the vote.

Officials said more than 30 bombings and a shooting hit 12 different areas of Iraq, leaving 50 people dead and making Monday the country's deadliest day since March 19.

No group immediately claimed responsibility for the attacks, but Sunni militants linked to al-Qaeda frequently attack both government targets and civilians in a bid to destabilise the country, and they have reportedly sought to intimidate candidates and election officials ahead of polling.

The deadliest attacks were in Baghdad, where eight bombings struck in seven neighbourhoods across the capital despite tougher checkpoint searches and heightened security.

Among them was a car bomb in a parking area used by vehicles making their way to Baghdad's heavily guarded airport, a rare bombing on the road famously known as ''Route Irish''.

In Tuz Khurmatu, 175 kilometres north of Baghdad, six people were killed and 67 wounded by three nearly simultaneous car bombs, and in Kirkuk, five people were killed and 44 wounded by six more car bombs.

Attacks elsewhere killed nine people and wounded 92 others.