CILEGON, Indonesia - A powerful 6.4-magnitude earthquake struck off the western end of Indonesia's Java island on Friday, shaking office buildings in Jakarta, officials said.

The quake struck off the coast near Ujung Kulon, about 260 kilometres west of the capital Jakarta, but there were no immediate reports of damage or injuries, officials said.

The US Geological Survey said the quake was of 6.5-magnitude and only 187 kilometres west-southwest of Jakarta, at a depth of 55.6 kilometres in the Sunda Strait.

Office towers in Jakarta bounced and swayed for about two minutes and people were seen moving into the streets as a precaution, but there were no signs of panic.

In Cilegon on the west Java coast, residents said the earth shook powerfully but there was no evidence of damage.

Geophysics Agency technical chief Suharjono told AFP the quake was the result of movement in the same plate that triggered a 7.6-magnitude quake on September 30, killing more than 1,000 people on Sumatra island.

But he said it was impossible to say whether the two events were related.

"We're not sure if the recent quake in West Sumatra and the current one are related. But the epicentres are in the same bloc... due to a clash between the Indo-Australian and Euro-Asian plates," he said.

Indonesia lies on the so-called Ring of Fire, an area of high seismic activity that produces hundreds of earthquakes a year.