The state government in India's Tamil Nadu state, which bore the brunt of the Indian Ocean tsunami, has issued a tsunami alert and it has warned people to leave coastal areas.
Police said aftershocks in the Andaman and Nicobar islands, near the centre of the huge earthquake that caused Sunday's tsunami, were "likely" to cause high waves.
But there were no immediate signs of giant waves today and the US Geological Survey said it was unaware of any aftershock large enough to trigger a fresh tsunami.
They said an aftershock would have to reach at least 7.5 magnitude and nothing had been recorded larger than 7.1 since Sunday.
Officials estimate Sunday's tsunami killed at least 12,500 people in India. Television footage from Nagappattinam, where more than 4,000 people died, showed panicked residents running through streets.