The explosions were likely to have come from the fuel tank of the ferry, which was carrying 129 passengers on board, most of them tourists.

The boat had completed about one-third of its journey to the resort island of Bali from Senggigi in Lombok when the explosion took place on Friday afternoon.

Among those injured were passengers from Australia, France, Italy, US, UK and New Zealand.

"No one has serious injuries. Most of the 25 patients suffered minor injuries from the impact," an official at West Nusa Tenggara hospital, Oxy Cahyo Wahyuni, said.

Two explosions hit the vessel 30 minutes after it set off from Senggigi with the second explosion breaking the windows and hitting the passengers," local water police official Khoirul Anwar said.

"We suspected that the explosion came from the fuel tank," Anwar said.

The local police is investigating to find the cause of the incident, he added.

A member of staff at Wahana Gili Ocean, the company running the ferry operation, described the situation of the boat.

"The passengers area was a mess, with seats overturned and scattered everywhere," Ismail, who only gave his first name, told AFP.

A spokesperson for Australia's Department of Foreign Affairs and Trade confirmed that four Australians were hospitalized and that all have been released from hospital.

The Indonesian archipelago of more than 17,000 islands is heavily dependent on ferry services but the industry has a poor safety record and fatal accidents are common.(+++)

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