Jakarta - Indonesia issued a tsunami warning after a powerful magnitude-6.6 undersea earthquake Tuesday morning struck parts of the western tip of Java and the southern Sumatra province of Lampung, triggering panic among office workers in Jakarta's high-rise buildings, seismologists said.

But the tsunami alert was cancelled about 40 minutes later after no tidal waves materialized, seismologists said, and there were no immediate reports of casualties or damage.

The quake's epicentre was in the Sunda Strait between crowded Java and Sumatra islands, 125 kilometres north-west of Ujungkulon on the south-western tip of Java, a sub-district 630 kilometres south-west of Jakarta.

It occurred at 10:07 am (0307 GMT), about 20 kilometres beneath the seabed, Indonesia's National Meteorology and Geophysics Agency (BMG) said.

The US Geological Survey later issued a bulletin that put the earthquake at a magnitude of 5.8 and at a depth of 43 kilometres.

"A tsunami warning had been canceled after no tidal wave took place following the quake," said the BMG's Taufik, who like many Indonesians goes only by one name.

Taufik added that there were no immediate reports of injury or structural damage from the quake, the latest in a series to rattle the country in recent days.

The quake was felt quite strongly in Bandar Lampung, the provincial capital of the southern Sumatra province of Lampung and nearby areas, but there were no reports of damage, said Suhardjono, another seismologist.

The quake triggered panic among thousands of people occupying high-rise buildings in the capital Jakarta, many of whom ran out of their offices, detik.com online news portal reported.

Indonesia, the world's largest archipelago, sits on the Pacific "Ring of Fire," the edge of a tectonic plate prone to seismic upheaval.

A major earthquake and subsequent tsunami struck on December 2004, leaving more than 170,000 people dead or missing in Indonesia's Aceh province and left half a million homeless.