Two roadside bombs and a bomb planted in a parked car detonated less than a kilometre (half a mile) from the revered Imam Ali shrine in the centre of Najaf, about 160 km (100 miles) south of Baghdad, officials said.

In addition to the two dead, at least 45 were wounded in the blasts, a police officer assigned to one of Najaf's two main hospitals said.

Hassan al-Zubaidi, deputy governor of Najaf province, said at least one person was killed and 72 were wounded in the coordinated attack.

"What happened today in Najaf is a part of what is happening in the whole of Iraq, an increase in violence ... They want to affect the coming election," he said.

"In any case, what happened today in Najaf is an indication that we need to reconsider the performance of our security forces."

A police source in Baghdad said the blasts had killed at least 25 people and wounded 72, but officials in Najaf denied the higher toll.

Najaf, in Iraq's Shi'ite south, has been relatively free of violence in the past year. The sectarian slaughter unleashed by the 2003 U.S. invasion has largely subsided across Iraq but U.S. and Iraqi authorities expect attacks to increase ahead of key parliamentary elections in March.