"A Lebanese suspect from the Hezbollah group has been taken into custody by Thai officials and police are investigating further," Chalerm Yoobamrung told Reuters.

"Following concern raised by the Israeli embassy about a possible attack by a group of Lebanese terrorists in Bangkok, Thai police officials had been coordinating with Israeli officials since before the New Year."

In Jerusalem, Israel's Counterterrorism Unit issued a "severe travel warning" to nationals, advising against travel to Bankok "in the near future", and to "avoid congregating at known spots favoured by Israelis, watch out for suspect items and not to accept packages from strangers in Bangkok".

Defence Minister Yuthasak Sasiprapha said Thai and U.S. intelligence officials were monitoring the movements of other individuals and were stepping up precautions in areas deemed to be at risk such as tourist sites and Bangkok's Suvarnabhumi airport.

A defence ministry source said Israeli intelligence had contacted Thai officials on December 22 with information that two or three suspects could be planning an attack in Thailand. However, the individuals travelled to the south and left the country.

The Israelis alerted Thai officials again on January 8 of the danger of an attack around January 13 to 15 in areas where there are often large concentrations of Western tourists, such as the Khao San Road, which is popular with young backpackers.

The arrest was made after the second Israeli warning, the source said, adding that Thai security officials were working closely with the United States and Israel.

Defence Minister Yuthasak said the Israeli embassy and synagogues could also be targeted and that the attacks could come in the form of car bombs.

"Thai officials had not intended to release the news at this time since it could have an impact on tourism and cause panic among citizens," he said, noting that the U.S. embassy naturally was concerned about the safety of Americans.

Earlier, the U.S. embassy had warned of a possible attack by "foreign terrorists" and told its citizens to be careful in areas of the capital frequented by tourists.

"We're warning all U.S. citizens to take caution when visiting public areas where Western tourists are known to gather in Bangkok," said Walter Braunohler, a spokesman at the embassy, declining to give further details.

Bangkok, a magnet for tourists with its vibrant nightlife and a transit point for those heading for Thailand's beaches, has gone through periods of violent political turmoil in recent years but threats of foreign attacks are rare.

Hezbollah, a Shi'ite Islamist group in Lebanon backed by Syria and Iran, is on the official U.S. blacklist of foreign terrorist organisations.

(Additional reporting by Sinsiri Tiwutanond and by Ori Lewis in Jerusalem; Writing by Alan Raybould; Editing by Jason Szep and Ron Popeski)

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