Witnesses described as "a horrible scene" parts of the Indonesian resort Island of Bali which were hit by up to four bomb blasts on Saturday.

Bali blasts
"It's a horrible scene," said Koman, a receptionist at the Graha Asih Hospital close to Jimbaran Bay. "Some people have had their heads blown off."

Koman said at least eight bodies were in the hospital morgue, and that doctors were treating at least 13 other people. Local terror analysts are saying the blasts have the markings of Al Qaida.

I Wayan Krisna said he witnessed the first bomb at a seafood restaurant on Jimbaran beach. "I helped lift up the bodies," he told the local El Shinta radio station. "There was blood everywhere." Krisna said he saw the severed head of a victim.

Putu Putra Wisada, spokesman at the Sangla Hospital in the capital Denpasar, said 11 dead were taken to the hospital. Wisada said eight Australians, two Americans and 28 Indonesians were admitted with injuries.

Another explosion hit the three-story Raja restaurant in the busy outdoor shopping centre of Kuta, about 30 kilometres away. Smoke poured from the building, which was badly damaged.

"People were running for their lives. Foreign tourists were wounded," said Yosi, 24, a shop owner in Kuta.

The bomb apparently went of on the second floor of the restaurant, said an AP reporter, who saw three bodies and at least five wounded.

Kuta resident Dewa Manik said he heard two blasts coming from the restaurant, which is popular with locals and foreigners.

Shattered glass littered bloodied streets around the Matahari Square shopping centre which had been packed with hundreds of people when the blast went off.

British tourist Daniel Martin told the BBC he was standing in a building next to the restaurant in Kuta when a "tremendous" explosion erupted.

"It was just sheer chaos with no one really taking control," Martin said, adding that "there were no police or anyone else around for a good while. It was everyone pitching in to help the wounded."

"There were people lying in the street with serious wounds, blood pouring into the street ... I was afraid to go into the actual restaurant for fear of what I might see in there."