BANGKOK –  Thai police were on Friday questioning a Lebanese man with alleged links to Hezbollah militants as the U.S. Embassy warned of a "real and credible" threat of a terrorist attack against American citizens in Bangkok.

Deputy Prime Minister Chalerm Yubamrung said Thai authorities received a tip-off before New Year's of a planned attack, which was said to target Israelis.

Subsequently, police detained on Thursday one of two suspects from Lebanon with alleged links to Hezbollah, he said. The man was held under immigration laws, and was being interrogated, he said.

Chalerm spoke hours after the U.S. Embassy in Bangkok sent an "emergency message" to American citizens earlier Friday warning of a possible terrorist attack.

The message said that "foreign terrorists may be currently looking to conduct attacks against tourist areas in Bangkok in the near future." It urged Americans to "keep a low profile" in public and to exercise caution in areas where Western tourists gather.

The statement gave no other details.

Ambassador Kristie Kenney told The Associated Press the threat was "real and very credible." She didn't give any other information.

It was the first U.S. warning of a foreign terror attack in Bangkok in recent memory.

Hezbollah, a Shiite Muslim militant group, is the most potent military force in Lebanon, far stronger than even the national army. It is backed mainly by Iran and Syria and is avowedly anti-Israel.

Friday's terror warning comes during a period of heightened tension over U.S. and Israeli responses to the prospect that Iran is going forward with developing nuclear weapons.

Iran sees possible U.S. complicity in a series of assassinations of its nuclear experts -- the latest Wednesday, when scientist Mostafa Ahmadi Roshan was killed by a bomb attached to his car by a passing bicyclist.