LAHORE, Pakistan (REUTERS) - Authorities at Lahore airport in Pakistan arrested four men suspected of trying to smuggle a foil-wrapped pistol and bullets onto a flight to Thailand in hand luggage, security officials said on Thursday.

The men, all Thais who had been studying at a religious school in Pakistan, were trying to catch a flight on Monday night when they were intercepted, four officials said.

It was not clear why one of the four men was carrying the pistol and several bullets wrapped in foil, or if any of the men have militant links.

"The boys are studying at a religious seminary," said one official.

"They were going back on vacation."

Another official said that the men were in their early 20s.

"One of them managed to clear all checkpoints and board the Bangkok-bound flight of Thai Airways while other three were caught on the third and the final checkpoint after a security official scanned their bags," he said.

The fourth man was detained after the other three identified him, he said.

The Thais were being interrogated, the officials said, and arrests had been made in northwestern Swat Valley, where the men studied, and the northwestern city of Peshawar.