BANGKOK (AP) — Thai police were questioning a Lebanese man with alleged links to Hezbollah militants as the U.S. Embassy and Israel warned Friday of a “real and credible” terrorist threat against Americans and Israelis in Bangkok. Police said a bombing had been planned and another suspect was at large.

The warning comes during heightened tension over U.S. and Israeli responses to the prospect that Iran is going forward with developing nuclear weapons. Lebanon-based Hezbollah, which has been accused of carrying out terrorist attacks in the Middle East since the 1980s, is avowedly anti-Israel and widely considered to act as a proxy for Iran.

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.

“At first we were told the Palestinians were behind it but it turned out to be the Hezbollah,” he told The Associated Press. In other interviews, he said Israel had provided the warning.

Chalerm said police detained a Lebanese suspect with alleged links to Hezbollah on Thursday.

Thai authorities had been “following two Lebanese men and called in one of them … for questioning,” Chalerm said. “Technically the two men have not committed any crimes under the Thai law, so we could only use the immigration law to keep this one suspect in custody,” he said.

At a late-night news conference, police later released a sketch of the second man, said to still be at large.

Metropolitan Police spokesman Piya Utayo said the description came from the man being questioned, who was being held at “a safe location.” The man, whose name was not given, was alleged to have told police the pair arrived before New Year’s and planning a bombing.

Piya said the missing suspect was still in Thailand, and urged people to be on the watch for him, especially in the Bangkok tourist neighborhoods of Khao San Road and Sukhumvit Road’s Soi 22. He said special police units were sent to those areas to search for the man, who was described as the senior of the two.

Chalerm spoke hours after the U.S. Embassy in Bangkok sent an “emergency message” to American citizens.

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 AP 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.

In Israel, the prime minister’s counterterrorism office also warned of “a clear and present possibility that a terror attack is planned against Israeli travelers in Bangkok.”

It recommended that Israelis refrain from visiting Bangkok, not congregate at sites known to be associated with Israelis in Bangkok and not accept objects from strangers. Thailand is a popular destination for young Israeli backpackers.

Chalerm said the danger has passed.

“I want to confirm and I am confident that we have the situation under control. And I can guarantee … no terrorist attacks will be allowed to take place. If they have disagreement, (they should) go fight somewhere else.”

Thai Defense Minister Yuthasak Sasiprapa also gave an account of the alleged plot, saying preliminary intelligence suggested that an attack would be carried out Jan. 13-15. He said there would be “an escalation of security measures” if the suspects were not found by Friday evening, but he did not explain further what that entailed.

Yuthasak said Thai authorities had not released news of the alleged plot because it would hurt the tourist industry and cause panic. He said intelligence reports said the planned attacks might be related to the U.S. activities concerning Iran.

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.

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.

Thailand has rarely been a target for foreign terrorists, although a domestic Muslim insurgency in the country’s south has involved bombings of civilian targets.

In 1994, an attempt to bomb the Israeli Embassy in Bangkok was abandoned when the driver of a massive truck bomb fled after a minor traffic accident. Several Iranians were arrested then but eventually released.