(Ahlul Bayt News Agency) - Multiple bomb explosions have rocked the southern Iraqi city of Karbala, killing at least 12 people and injuring 100 others, witnesses report.

 The series of explosions in the central city also wounded nearly 100 people and caused major damage to buildings, leading security forces to cordon off the scene and close all entrances to Karbala.

 An initial roadside bomb at 9:30 am (0630 GMT) in the centre of the city, 110 kilometres (70 miles) south of the capital, was followed by three more blasts once emergency services arrived, according to a police officer and a provincial government official.

 "The bomb attacks in Karbala today have so far killed nine people and there are 99 people wounded," said Alaa Hammudi, head of Karbala province's health department. He warned that the toll could rise further.

 A news agency journalist at the scene reported seeing several bodies covered in blood being taken away by paramedics, and major damage to buildings, with some houses completely collapsed.

 Security forces cordoned off the area in the aftermath of the attacks, the journalist said. An interior ministry official said entrances to the city had been closed.

 Karbala is a predominantly Shiite city that is home to the mausoleums of Imam Hussein and his half-brother Abbas.

 In the western city of Ramadi, meanwhile, two roadside bombs killed two people and wounded six others, including two young girls, a police officer and an anti-al Qaeda militiaman said.

 An initial explosion at the home of tribal chief Mohammed Awwad killed a woman and wounded the girls, the security officials said. The second blast, which occurred when police arrived at the scene, killed a man and wounded four others, including three policemen.

 Ramadi is the capital of Anbar province, a key Sunni insurgent base in the years after the US-led invasion of 2003, but since 2006 local tribes have sided with the American military and day-to-day violence has dropped dramatically.