(Adds relief agency saying no casualties)

JAKARTA, Dec 2 (Reuters) - An earthquake measuring 6.0 on the Richter scale shook the western part of Indonesia's Java island on Sunday, but there were no immediate reports of damage or casualties, the meteorology agency said.

The undersea quake had a depth of 32 km (20 miles) and was centred 78 km southeast of Ujungkulon in the western tip of Java.

An official at the meteorology agency said the quake was felt strongly in the Pelabuhan Ratu resort area but there were no reports of injuries.

"There have not been any reports on damage or casualties so far," said Radito, an official at the National Disaster Relief Coordinating Agency.

Indonesia sits on the so-called Pacific Ring of Fire, a very active seismic region where several tectonic plates meet, and is subjected to frequent tremors.

In December 2004, a powerful quake off Aceh province triggered a huge tsunami in the Indian Ocean, killing around 230,000 people in neighbouring countries with most of the deaths in Aceh. (Reporting by Ade Mardiyati and Ahmad Pathoni)

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