Sri Lanka has disconnected power supply and suspended railway services to coastal areas after issuing a tsunami warning following a massive 8.6-magnitude earthquake off the west coast of Indonesia's northern Sumatra, government officials said in Colombo on Wednesday.

The state Ceylon Electricity Board has disconnected electricity to all coastal areas to prevent fire and other disasters following the tsunami warning, according to the Government Information Department.

Railway services to coastal areas have also been stopped to prevent any casualties.

Several areas in the capital as well as the rest of the country felt tremors but no damage of property and causalities have been reported yet, police said.

Officials of the Disaster Management Centre have issued a precautionary tsunami warning asking people in the southern, eastern and Colombo region of the country to move inland.

Thousands of people walked out of their office buildings and stayed outside on the pavement as tremors were felt.

"I was on the seventh floor of my office building when we felt it... Everyone rushed out of the building," said office executive Chaminda Amerasinghe.

Sri Lanka lost around 40,000 people during the last Indian ocean tsunami in 2004.