A massive earthquake measuring 8.2 on the Richter scale on Monday night struck the Indonesian island of Sumatra raising fear of another tsunami and causing panic along the entire southeastern coastal areas of India and Andaman and Nicobar islands.

A general alert has been sounded in Tamil Nadu, Kerala [Images] and Andaman and Nicobar, one of the worst hit by the tsunami that hit the coastal areas on December 26.

Mild tremors were felt in Port Blair and Katchal Island.

Soon after the quake � the US Geological Survey said it measured 8.7 - struck the Sumatra Island at 2140 IST, the Centre activated its  Disaster Management Team in Delhi and issued warning to coastal states of Orissa, Andhra Pradesh, Tamil Nadu, Pondicherry, Kerala, Karnataka, Lakshadweep and Andaman and Nicobar islands asking them to take all precautions and remain on the highest state of preparedness.

Prime Minister Manmohan Singh [Images] spoke to Andaman and Nicobar Lt Governor Ram Kapse even as the army, navy and the air force were put on alert and armed forces and paramilitary personnel asked to help civil authorities in coastal areas if needed.

Home Minister Shivraj Patil spoke over phone to Defence Minister Pranab Mukherjee and reviewed the preparedness of the armed forces.

People in Tamil Nadu, which bore the brunt of last year's tsunami, have been asked to move 500 metres away from the coast as a precautionary measure.  

Patil said authorities in the coastal areas have been asked to carry out evacuation in case there are indications of tsunami.

He said the control rooms at the Centre as also at state levels will be working throughout the night. He asked the people not to panic

Even after over five hours of the quake, there have been no reports of tsunami hitting the Indian coastline.