Thousands of workers fled from swaying high-rise office buildings in Bangkok yesterday after a strong earthquake struck in western Laos, about 750 kilometers to the north.

There were no initial reports of major damage or casualties from the quake, which was measured at magnitude 6.1 by the United States Geological Survey and Thailand's Meteorological Department, and was centered in a remote, sparsely settled region.

The quake occurred at 3:56pm at a point 166 kilometers west-northwest of the Laotian city of Luang Prabang, said the USGS.

Many offices in Bangkok's business districts were evacuated, with their panicky occupants gathered in the street. Many went home early from work.

The quake was felt more strongly in northern Thailand, with Smith Dharmasaroja, chairman of the National Disaster Warning Center, saying it had been the strongest one known to hit the area.

He told Thai TV Channel 3 there had been almost 10 aftershocks, and warned people not to return to cracked houses for at least 24 hours. He said landslides were also a possible threat.

The quake was clearly felt in the northern Thai city of Chiang Mai, a popular tourist destination 259 kilometers southwest of the epicenter, but a spokesman for the Disaster Mitigation and Prevention Center there said there were no reports of damage.

A Lao Foreign Ministry spokesman, Yong Chanthalansy, said by telephone from the Laotian capital Vientiane that the earthquake lasted for about 10 seconds. He and another resident of the capital said it was not felt there, 343 kilometers to the southeast.

Yong said there were no initial reports of casualties from the area and that there had been no panic.

In Luang Prabang, several residents contacted by phone described feeling "disoriented" for a period of up to two minutes by the shaking of the Earth, while others noticed nothing at all. No damage was immediately visible in the city. A foreign businesswoman at her shop in the city center said she felt "almost drunk" following a tremor that caused a chair to rock.

In Chiang Saen district of Thailand's Chiang Rai Province, about 60 kilometers from the epicenter, a cement and brass part from the top of the Jomkitti pagoda was damaged and some decorative glass pieces fell off, but damage was not extensive, said Prachon Pradsakul, director of the Disaster Mitigation and Prevention Center.

In Mae Sai District of Chiang Rai Province, the border area of Thailand nearest to the epicenter, district chief Pongkan Piyapongtulakom said there were no initial reports of damage or casualties but the officials were still surveying buildings.