Tsunami warning issued for Cocos Islands

The Cocos Islands, in the Indian Ocean northwest of Perth, are on tsunami watch after a 6.6 magnitude underwater earthquake.

The warning was issued at 9.41pm (AEST) on Saturday after an undersea earthquake struck at 9.11pm, the Australian Bureau of Meteorology says.

The tsunami warning for the Australian territory was issued for the marine environment of the Cocos Islands, with dangerous rips, waves and strong ocean currents possible for several hours.

While evacuations are not required, people are being advised to move away from beaches, harbours, marinas, coastal estuaries and rock platforms.

Meanwhile, vessels already at sea have been told to stay offshore in water at least 25 metres deep until further advised.

"Do not go to the coast to watch the tsunami," the bureau advises.

"At this stage, no tsunami waves have been observed that may threaten Australia," the bureau advises.