A suicide car bombing has killed at least seven people and wounded 15 others at a security checkpoint in western Iraq, police have said.

Security and hospital officials said three policemen were among those killed on Monday when a suicide bomber drove a car loaded with explosives into a checkpoint near Ramadi, the capital of western Anbar province.

Mohammed Hussein Alwan, a 40-year-old farmer, said he was riding in a lorry about 200 metres from the attacker's car when the blast occurred.

"I ran to the site and saw five burning cars and a child who was thrown by the explosion and landed on the top of a car," he was reported by The Associated Press as saying.

"I tried to approach him to see whether he was alive or dead, but the police started to open fire in all directions and we had to run away," Alwan said.

Sporadic attacks

Ramadi was once a key al-Qaeda stronghold following the US-led invasion of 2003, but violence has significantly decreased since 2006, when local tribes sided with the US military.

Sporadic attacks still continue in the province, with a series of bombings in July prompting Iraqi security forces to declare a state of emergency there.

The withdrawal of US forces from towns and cities in Iraq at the end of June had raised concern that the country would see a resurgence in violence.

Over the last two months Iraq has seen a number of deadly attacks, including a bombing at government ministries in Baghdad in August, that killed almost 100 people.

There have also been a series of attacks in areas of northern Iraq where tension is high between majority Arabs, ethnic Kurds and other minorities.

The violence has shaken public confidence just months ahead of January's national elections.