Winehouse is banned from travelling to the Grammys

The American embassy in London has rejected the singer Amy Winehouse's application for a US visa, meaning she won't be able to attend this Sunday's Grammy Awards.

Winehouse, who is undergoing treatment for drugs and alcohol dependency, has been nominated for six awards at the ceremony, including best new artist, album of the year, and song of the year for "Rehab", released in 2006.

The news – which comes soon after she was questioned by police over a video apparently showing her smoking crack cocaine – will come as a blow to the soul singer. But a representative for Winehouse played down the development.

"Amy has been treated well and fairly by the embassy staff and thanks everyone for their support in trying to make this happen. There will of course be other opportunities and she looks forward to visiting America in the near future," the representative said.

"Amy has been progressing well since entering a rehabilitation clinic two weeks ago and, although disappointed with the decision, has accepted the ruling and will be concentrating on her recovery."

Though increasingly criticised over shambolic performances before she decided to go into rehab, Winehouse – who is loved and hated in almost equal measure in the UK – remains popular in America.

Despite cancelling a tour and several promotional appearances there last year, she has sold one million copies of her Back to Black album. Before the crack cocaine allegations – which came with a video released by The Sun newspaper last month – she was expected to be able to travel to the awards in Los Angeles this weekend.

The singer checked into a private clinic in central London last month after the latest in a string of near non-stop allegations about her use of drugs.

In a statement, her record label, Universal, said: "She has come to understand that she requires specialist treatment to continue her ongoing recovery from drug addiction. Amy entered the facility by mutual agreement and continues to receive the full support of all concerned."

The move came after Winehouse's outspoken father, Mitch, revealed that he had attempted to get his daughter sectioned under the Mental Health Act, and that the request was turned down because it could not be proved that she would harm herself.