BANGKOK -- The Thai immigration chief Wednesday declared former British glam rocker Gary Glitter "persona non grata" and threatened to return him to Vietnam, where he served prison time for child sex offences.

Lieutenant General Chatchawal Suksomjit said Glitter had refused to board a plane to London and would not be allowed to enter Thailand.

"We will have to repatriate him back to Vietnam, because he is on our watch list as persona non grata. Thai immigration cannot let him enter," Chatchawal told AFP.

"He is still in the transit area," at the Bangkok international airport, he said.

Glitter, 64, left Vietnam late Tuesday after serving two years and nine months in prison.

He had been arrested there in late 2005 and convicted the following year of committing obscene acts with two girls then aged 11 and 12 in the southern resort town of Vung Tau.

The terms of Glitter's sentence called for his deportation upon his release, and it was not clear if Vietnam would allow him to return.