Beyonce Knowles is releasing a charity single to raise money for the victims of the 9/11 terrorist attacks.

The singer has recorded a version of 'God Bless The USA' which will be available to download from iTunes and her official website today and all proceeds from the sales will go to New York Police and Fire Widows' and Children's Benefit Fund.

The charity was set up in 1985 to help the relatives of cops and fire-fighters killed in the line of duty and it has played a key role in assisting the families who lost loved ones when terrorists hijacked planes and crashed them into the World Trade Center on September 11, 2001.

The 29-year-old pop star originally recorded the track - which was penned and performed by country artist Lee Greenwood in 1984 - in 2008 for the election campaign of current American President Barack Obama but it was never released.

The track was debuted on CNN talk show 'Piers Morgan Tonight' in the US yesterday evening.

Piers posted a series of comments from Beyonce about the song on his twitter account which read: "We were all affected by the tragedies of 9/11 and continue to keep the families who lost loved ones close to our hearts . Lee Greenwood, the writer of the song, is also donating his proceeds to help the 9/11 families . Thank you Piers Morgan and CNN for helping to get the message out to everyone about this."