Twin suicide bombings at a Shiite mosque in north Iraq were the deadliest in attacks nationwide that killed 15 people Saturday, amid a surge in bloodshed authorities have failed to quell.

The violence, which has killed more than 200 people in the past week alone, has forced Iraq to appeal for international help in combatting militancy just months ahead of its first general election in four years.

Officials have also voiced concern over a resurgent Al-Qaeda emboldened by the civil war in neighbouring Syria which has provided the jihadist network's front groups in Iraq with increased room to plan operations.

Attacks on Saturday struck mostly in the north, although Baghdad was also hit.

The deadliest violence was in Tuz Khurmatu, where a suicide car bombing followed by a suicide attack targeting a Shiite mosque killed at least 10 people and wounded 45, according to a police colonel and town mayor Shallal Abdul.

The initial blast was at 5:30 pm (1430 GMT) near the Imam Ali mosque, which is in the middle of a crowded market and near offices of the Patriotic Union of Kurdistan, the party of ailing Iraqi President Jalal Talabani.

Shortly afterwards, a suicide bomber blew himself up at the entrance to the mosque.

"I am sure the attack was carried out by Al-Qaeda," said Abdul.

"There is major destruction and damage in the area, because it (the mosque) is located in the centre of a market."

Tuz Khurmatu, an ethnically mixed town, lies in the middle of a tract of disputed territory that Iraq's Kurds want to incorporate into their autonomous northern region over the objections of the central government.

Militant groups often exploit poor communication between the two sides' security forces in order to carry out attacks, and Tuz Khurmatu is frequently hit by violence.

Unrest in Baghdad and two cities in the north -- Tal Afar, which is mostly Shiite Turkmen, and Sunni Arab Tikrit -- left five other people dead, officials said.

No group has claimed responsibility for the rise in violence, but Sunni militants linked to Al-Qaeda often launch attacks on both Shiites and Sunnis, ostensibly in a bid to undermine confidence in the authorities.

The government and security forces have insisted that raids and operations across much of western and northern Iraq, areas dominated by the country's Sunni minority, are having an impact.

But diplomats, analysts and human rights groups say the government is not doing enough to address the root causes of the unrest, particularly disquiet among Sunnis over alleged mistreatment at the hands of the Shiite-led authorities.

Prime Minister Nuri al-Maliki has called for Washington's help in the form of greater intelligence-sharing and the timely delivery of new weapons systems.