LONDON (Reuters) - Soul singer Amy Winehouse has been questioned by police over an allegation of drug possession, a police source said on Wednesday.

The 24-year-old singer, who entered a clinic last month to treat her well-publicized drug addiction, was interviewed under caution but not arrested.

Media reports said the allegation stems from video stills published in a newspaper last month that appeared to show her smoking crack cocaine.

A report in the Sun newspaper said officers questioned Winehouse for two hours at a north London clinic after seizing the footage.

It said the video was shot hours before Winehouse went to a court hearing to support her husband Blake Fielder-Civil, who is fighting charges related to a pub brawl.

The Metropolitan Police said in a statement: "The woman has not been arrested but is being interviewed under caution. Police inquiries into the matter are continuing."

Winehouse's record company Universal Music Group said last month she had decided she needed specialist treatment to help her recover.

Winehouse is one of Britain's top-selling singers, winning critical and commercial success with her album "Back to Black."

She has been nominated for six Grammys including Album of the Year, Song of the Year and Best New Artist.

The album's hit single "Rehab," with the line: "They tried to make me go to rehab. I said 'no, no, no"' has been called the anthem of celebrity trash culture.

In October 2007, she and her husband were arrested at a Norwegian hotel for marijuana possession.

She still wants to attend the Grammy ceremony in Los Angeles on Sunday, although there is no guarantee she will get a U.S. visa, the Sun said, quoting an unnamed friend of the singer.

Her publicist was not immediately available for comment.

(Reporting by Peter Griffiths)
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