Washington - An earthquake measuring 6.4 on the Richter Scale has struck in the Pacific Ocean off the coast of Japan, the US government reported Monday.

The earthquake took place at 2007 GMT about 170 kilometres southwest of Tokyo, the US Geological Survey in Denver, Colorado, said.

The USGS reported the earthquake moments after announcing 7.6 magnitude earthquake occurred in the Indian Ocean, about 262 kilometres north of India's Andaman Islands.

The quake prompted the Pacific Tsunami Warning Centre in Hawaii to issue a tsunami watch for Bangladesh, India, Indonesia, Myanmar and Thailand.(dpa)