Hawks are being recruited to scare off the Trafalgar Square pigeons, allowing American glam rockers the Scissor Sisters to perform a free open-air concert.

The flamboyant US band have been given permission by Ken Livingstone to take over the square next month.

But organisers are now frantically recruiting 10 birds of prey to ensure that the square's notorious pigeon population does not ruin the show.

The birds will be in addition to the Harris Hawk used by Ken Livingstone in a bid to deter pigeons from roosting in the square after being fed each morning.

A text lottery for the tickets started at 9am today, with 4,500 pairs up for grabs. All proceeds will go to the Global Fund that was set up by U2 frontman Bono to help fight Aids in Africa.

Organisers say they have embarked on a search for as many red feather boas and trilby hats as they can find to give to concertgoers to create a massive spectacle. The event starts at 6pm on Saturday 16 September.

It will be the second time the Mayor has given permission for a massive pop concert on the worldfamous square. David Gray and Morcheeba played there in 2003.

The event is sponsored by mobile phone company Motorola to promote the red MOTOSLVR - the first Motorola handset created to contribute to the fight against Aids with £10 from every purchase.

The band, whose hits include Mary and Take Your Mama, will be promoting their second album Ta-dah, released on 18 September.

Tickets can be obtained by sending a text to 80855* with the word MOTORED.

The cost of the text will be £1.50 plus standard network charges, with all profits going direct to the Global Fund.

The free prize draw will remain open for 10 days with lines closing at midnight on 27 August.

Winners will be chosen at random. All entrants will be notified in the week commencing 28 August.

Band member Babydaddy said: "London is our spiritual home, and the UK gave us our first and longest-lasting embrace. To be able to play this event in conjunction with the (RED) campaign and to launch our new album seemed the perfect match."