Foreign Minister Kantathi Suphamongkhon instructed the Thai embassy in London to monitor the situation and report back to Bangkok regularly.

People with a real need to visit the UK should get the latest updates from agencies, including the Foreign Affairs Ministry, before departure and should observe all advisories from British authorities, the ministry's statement said.

Thais in the UK were not panicking over the threat, ministry spokesman Kitti Wasinondh said.

The embassy in London recommends Thais refrain from gathering in public places, he said.

Caretaker Prime Minister Thak-sin Shinawatra said he instructed Thai Airways International to perform thorough checks on all passengers with carry-on luggage but saw no need to halt flights.

The government expects the risk might not expand to Asia, he said.

THAI experienced no cancellations, and its two flights to London operated on schedule, said Surapol Isarangkun, director for emergency operations at the flag carrier.

The two flights were not disrupted by the closure of Heathrow Airport, as they were scheduled to land at 6.45am and 6.30pm while the airport was closed from 8.45am-1pm.

"But passengers flying from London to Bangkok could suffer a delay," he said.

The national airline said it stood ready to comply with British authorities if they step up security measures.

THAI said in a news release that one of its flights departing Heathrow for Bangkok yesterday afternoon was expected to depart about an hour late because of the new carry-on luggage restrictions.

But no flights from Thailand to London have been cancelled, said Somchai Sawasdeepon, a senior official from Airports of Thailand.