A strong 6.4 quake rattled Indonesia's Bali island today, hours after a quake struck Sulawesi island, but there were no immediate reports of major damage or serious casualties from either.

The Bali quake hit at 6:06am (7.06am Malaysian time), at a depth of 36 kilometres, according to Indonesian geophysics agency.

The epicentre was 101 kilometres southeast of Nusa Dua, an enclave of resorts located in the southern part of the holiday island.

"There are no indications that the tide in Kuta is rising. So it's pretty safe here," Kuta district police chief Dody Prawira Negara said.

Health ministry crisis centre head Rustam Pakaya said that eight people suffered fractured bones and a pregnant woman was taken to hospital.

"There are no deaths or major damages, only cracks in several buildings," Pakaya said.

No tsunami warning

A 5.8-magnitude quake hit Sulawesi island several hours earlier, seismologists said.

The tremor struck at 3:34am (2:34am Malaysian time), at a depth of 103 kilometres, according to a revised report by the US Geological Survey (USGS).

The epicentre was 110 kilometres north-northwest of Ternate in the Moluccas and 260 kilometres east of Manado on Sulawesi.

The Hawaii-based Pacific Tsunami Warning Center did not release a tsunami warning for either event.

Indonesia sits on the Pacific "Ring of Fire," where the meeting of continental plates causes high volcanic and seismic activity.

Malaysian students 'safe and sound'

Meanwhile, Malaysian Students Department director in Indonesia Dr Junaidi Abu Bakar said all Malaysian students in Bali are safe.

He said the department contacted the students to verify their conditions soon after the earthquake was reported.

"Alhamdulillah, they are all safe and sound," he told Bernama here.

There are 239 Malaysian students in the resort island.

Junaidi said some 80 of the students, when contacted, said that they were already at their family homes in Malaysia to celebrate the Aidilfitri.

- AFP