Lily Allen has been barred from entering America after being interrogated at US customs for five hours over her criminal record.

The singer was stopped by immigration officers at Los Angeles airport on Sunday where she arrived to film a video with rapper Kanye West and attend the MTV video music awards. Allen was released after being told her work visa had been cancelled because she was arrested in London in March following an alleged assault on a photographer. The Myspace star received a police caution after she was said to have attacked the man outside a nightclub. Allen's American tour, scheduled for next month, is now under threat.

Allen, 22, said: "I am trying everything I can to sort this out. I don't like letting my fans down.

"It is my intention to play my American dates in September.

This depends on the authorities granting me a new work visa. I am sure that we can sort this out."

The singer, who had flown in from Australia, recently performed in front of Prince William and Prince Harry at the memorial concert for Diana and has previously documented run-ins with airport staff on her blog. On her Myspace page in May, she wrote about being detained by customs officials in New York: "I was told it was because I am a musician."

The daughter of film and music star Keith Allen, the singer achieved her first number one with Smile last July.