At least 10 people were killed and 25 wounded when a suicide bomber blew himself up at a funeral service for a Sunni Muslim tribal sheikh in northern Iraq.

No one is claiming responsibility for the attack, but suicide bombers linked to al Qaeda have stepped up attacks this year. They frequently target Sunni leader's followers considered supportive of Iraq's Shi'ite-led government.

The attack took place in a town northeast of Baghdad among a crowd of mourners.

Iraq is suffering its worst wave of violence in at least five years.

The government says the civil war in Syria is stirring sectarian violence in Iraq.