Police said the first blast tore through the Raja restaurant in the shopping district of Kuta, the scene of the 2002 bombings, which left 202 people dead, mostly foreign tourists.
Minutes later, two further explosions ripped through a pair of beachfront restaurants 30 kilometres away in the picturesque fishing village of Jimbaran.
Indonesian President Susilo Bambang Yudhoyono immediately condemned the latest outrage and vowed to hunt down the perpetrators. "These are clearly terrorist attacks because the targets were random and public places," he said.
A French diplomat who visited two hospitals in Bali on Saturday said at least 32 people had been confirmed dead and 101 had been injured in the blasts, which came during the peak tourist season.
At the scene of the Kuta bomb, bodies lay covered by bloodied blankets as police moved among crowds of onlookers using flashlights to pick their way through the gutted interior of the restaurant.
Television images from Sanglah hospital in the Bali capital Denpasar showed several foreign tourists, wearing nothing but shorts, being treated for injuries.
Australia, which lost 88 citizens in the 2002 attacks, confirmed at least one national had been killed and three others injured.
Indonesian reports listed at least one Japanese national killed and five Koreans injured. A British foreign minister, Lord Treisman, told Britain's Sky News that US, Australian, Japanese and Korean tourists were among the injured.
World leaders immediately offered their support and uttered condemnation after the bombings, French President Jacques Chirac saying he was "stunned and saddened" by the news.
British Prime Minister Tony Blair condemned the attacks "in the strongest possible terms" and said his government would help in any way it could.