Stars including Oscar-winning actor Colin Firth and singers Annie Lennox, Emma Bunton and Mollie King have donated designer clothes and rare memorabilia to a charity auction.

Former Spice Girls star Bunton and The Saturdays singer King have handed over two dresses to an online auction to raise cash to prevent the transmission of the deadly Hiv virus from mothers to their children.

Firth has donated signed props from his Academy Award-winning movie The King's Speech, ex-Eurythmics star Lennox has offered up some personal artwork, and her model daughter Tali has donated a jewellery box.

The sale, taking place on auction website, will raise money for the Mothers2mothers charity, which aims to slash the transmission of Hiv from mums to children in sub-Saharan Africa through education programs.

Bunton says, "This beautiful dress was handmade for me and I loved wearing it, but I'm delighted to donate it to such a good cause. Mothers2mothers are doing amazing work in sub-Saharan Africa, helping mothers protect their babies from Hiv infections."

Firth adds, "I'm delighted to support Mothers2mothers by offering this autographed package of King's Speech memorabilia. I have enormous respect for the work Mothers2mothers are doing to protect babies from Hiv, and hope this auction is a great success."

The auction will be held throughout March (13).