Police have questioned Amy Winehouse under caution over a video which allegedly shows the singer smoking a crack-cocaine pipe.

A Scotland Yard spokesperson said that the singer was questioned in relation to an allegation of unlawful possession of a controlled drug.

The video, which appeared in The Sun newspaper last month, prompted Winehouse’s record label, Universal, to hold crisis talks over the singer’s future.

In the footage Winehouse appears to admit to having just taken six valium pills in order to “bring myself down”.

The newspaper also claim that in the video, which was reportedly shot in Winehouse’s flat, the singer takes a combination of crack, cocaine and powdered ecstasy.

Winehouse was admitted to the Capio Nightingale clinic in London the day after the footage was published by the newspaper.

Yesterday (February 5th), it emerged that the singer had been allowed special escorted leave from the clinic in order to apply for a US visa.

Winehouse needs the work permit in order to travel to the Grammy awards in America on Sunday, where she is nominated for six awards, reports the BBC.