Gunmen have shot dead television presenter Nawras al-Nuaimi in northern Iraq, as attacks across the country left 20 people dead.

Al-Mosuliyah TV and police said that Nuaimi was murdered as she was walking near her home in Mosul, 400 kilometres northwest of Baghdad on Sunday night.

The presenter's death takes the number of journalists killed in Iraq since October to six and she is the fifth journalist killed in the northern city during the same period.

The mostly-Sunni Arab city is one of the most dangerous areas in Iraq, with fighters frequently carrying out attacks and reportedly extorting money from shopkeepers.

Also in Mosul, a roadside bomb missed an army patrol but killed two civilians and wounded four, authorities said.

In the town of Sadiyah, 95 kilometres north of Baghdad, police said gunmen killed a Health Ministry employee and his family early on Sunday.

Police said the attackers used guns fitted with silencers and broke into the man's home and killed him, his wife, two sons and their 10-year old daughter as they slept.

In the Waziriyah neighborhood of northern Baghdad, police said a bomb attached to a bus killed two commuters and wounded seven.

Later on Sunday, police said a car bomb exploded near a restaurant, killing three people and wounding four others in eastern Baghdad.

In Baghdad's northeastern suburb of Husseiniyah, four people were killed and six wounded in a car bomb explosion targeting a commercial street.

Danger for journalists

Police said three people were killed and eight others wounded when a sticky bomb attached to their bus went off in the Shia neighbourhood of Sadr city.

Health officials confirmed the death toll for all attacks to the AP news agency. All officials spoke on condition of anonymity because they were not

authorised to speak to journalists.

Violence has been on the rise in Iraq since a deadly crackdown on a Sunni protest camp in a northern town in April.

Iraq has come in for repeated criticism over shortcomings in media freedom, and ranks first in the Committee to Protect Journalists' Impunity Index, which tracks unsolved murders of journalists.

On December 5, Kawa Germyani, the editor-in-chief of the news website Rayel and a correspondent for the Kurdish- language newspaper Awene , was killed outside his home in town of Kalar, south of the Kurdish Iraqi city of Sulaymaniyah, the Committee to Protect Journalists said.

Kawa had announced on his Facebook page that he was going to a publish a report on corruption just before he was murded, according to The Kurdistan Tribune .

Following that killing, media rights watchdog Reporters Without Borders said it was "worried about the very dangerous climate for journalists both in Iraqi Kurdistan and the rest of Iraq, and about the impunity enjoyed by their attackers and killers."