Two pals were barred from entering the U.S. after innocent tweets joking about "destroying America" were picked up by the country's anti-terror cops, The Sun reports.

U.S. special agents monitoring Twitter spotted Leigh Van Bryan's messages weeks before he left for a holiday in Los Angeles with pal Emily Bunting.

Leigh, who also quipped about "digging up Marilyn Monroe" on Twitter, said they were treated like terrorists on arrival at a Los Angeles International Airport. The pair were held by armed guards and quizzed for five hours before being handcuffed, put in a van with illegal immigrants and locked up overnight.

They spent 12 hours in separate holding cells and were then put on a flight home.

Leigh, 26, was kept under armed guard in a cell with Mexican drug dealers. The Department of Homeland Security flagged up Leigh as a potential threat when he posted a Twitter message to his pals ahead of his trip to Hollywood.

It read: "Free this week, for quick gossip/prep before I go and destroy America".

Despite telling officials at LAX airport the term "destroy" was British slang for partying, the pair were held on suspicion of planning to "commit crimes".

Irishman Leigh, a bar manager from Coventry, said: "It's almost funny now but at the time it was really scary.