Gorontalo province governor Fadel Muhammad said he ordered residents to leave coastal areas after the strong earthquake shook the island at 3:22 pm (0722 GMT).

"I have ordered the people on the coastline, through the radio, to evacuate... I have also instructed all district heads to evacuate the people from the coast," Muhammad told ElShinta radio.

"I am taking the safe (solution)," he added.

Indonesia's third tsunami alert in a week came after about 600 people died in massive waves which crashed against Java island's southern coast on Monday.

But there were no reports of tsunamis 30 minutes after Sunday's earthquake 90 kilometres (56 miles) south of Gorontalo on Sulawesi's southern coast.

Officials said the quake's depth 71 kilometres (44 miles) under the Tomini bay seabed probably ruled out a repeat of last week's killer waves.

An officer at Gorontalo province police headquarters could not confirm evacuations were taking place.

"We have no report on a mass evacuation yet," he said.

Police contacted in various towns along Tomini bay said people ran outside buildings when the earthquake hit.

But there was no mass panic and no reports of damage or injuries, they said.

On Monday, a 7.7-strength undersea temblor triggered a tsunami that lashed the south coast of Java island, killing at least 596 people.

Two days later, a 6.2-magnitude quake sparked a tsunami warning for residents in west and south Sumatra.

Indonesia, which sits on the "Pacific Ring of Fire", where continental plates meet causing frequent seismic and volcanic activity, was the nation worst hit by the December 2004 Asian tsunami.

Some 168,000 people were killed in Aceh province when a 9.3-magnitude quake unleashed massive walls of water that reached 11 Indian Ocean nations, killing a total of 220,000.

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