Sri Lanka reports no wave, Thailand experienced some smaller wave, but no major damages.

This alert was issued after a 8,7 magnitude earthquake hit the West Coast of Northern Sumatra, Indonesia Wednesday. An after shock measured 8.2 was recorded hours later/

The quake struck 308 miles southwest of the city of Banda Aceh, on the northern tip of Sumatra island, at a depth of 20.5 miles, the U.S. Geological survey said.

According to the Jakarta Post the first Tsunami waves are expected to hit Sumatra at 16:21h local time (10:21 GMT) Indonesia issued a tsunami warning Wednesday .

Indonesian President Susilo Bambang Yudhoyono said that there was "no tsunami threat, although we are on alert," in a televised speech from the Presidential Palace in Jakarta on Wednesday afternoon, according to Reuters.

The earthquake's sideways motion in Sumatra make a tsunami less likely, Bruce Presgrave, of the United States Geological Survey, told the BBC.

“We can’t rule out the possibility, but horizontal motion is less likely to produce a destructive tsunami,” the BBC reported him saying.

UK Prime Minister David Cameron has pledged Britain's support to Indonesia in the wake of an earthquake off Aceh province as he visited Indonesia.

Speaking at a joint press conference with the Indonesian President in Jakarta, the Prime Minister said Britain "stood ready" to help in any way necessary.

He arrived in Indonesia Wednesday morning but reports suggest the 8.9 magnitude earthquake was not felt in the capital.

Mr Cameron said he was "hugely concerned" by news of the quake, telling Susilo Bambang Yudhoyono: "Our thoughts should be with those who are affected.

Said, an official at Indonesia’s Meteorology and Geophysics Agency who goes by only one name, said a tsunami warning has been issued for Aceh, West Sumatra, North Sumatra, Lampung and Bengkulu. The tsunami was expected to reach Aceh at 4:31 p.m.

According to Metro TV, traffic was chaotic Wednesday afternoon in Banda Aceh as people flee coastal areas for higher ground in the east. Power and internet is reportedly down in the provincial capita.

In Padang, hospitals are reportedly evacuating patients from the building.

The quake was felt as far away as the Thai capital, Bangkok, and in southern India, residents said. Hundreds of office workers in the Indian city of Bangalore left their buildings, workers there said.

The quake was in roughly in the same area as a December 26, 2004, quake of 9.1 magnitude, which sent huge tsunami waves crashing into Sumatra, where 170,000 people were killed, and across the Indian Ocean.

In all, the 2004 tsunami killed about 230,000 people in 13 Indian Ocean countries, including Thailand, Sri Lanka and India.

The 2004 quake was at a depth of 18 miles along a fault line running under the Indian Ocean, off western Indonesia and up into the Bay of Bengal.

The quake was also felt in Sri Lanka and the southern Thai holiday island of Phuket, both of which were hit hard by the 2004 tsunami.