Victoria Beckham has told how she wants to use what she has to "make a difference" as she made a impassioned speech at the United Nations.

The former Spice Girl-turned-designer gave the talk at a press conference at the UN building in New York after being named a Goodwill Ambassador for the UNAIDS campaign.

The mum-of-four said she was honoured to be a part of the programme, which works towards ensuring that children are born without HIV and that women and children affected by the virus have access to medicine.

Victoria said: "I'm a mother, I'm a woman, I want to do whatever I can do to lend my voice, raise awareness. This is something I feel very passionately about."

The star visited HIV clinics in Cape Town, South Africa, this year and said it was "a life-changing experience".

She said: "I was so touched by the women I met and felt inspired. I came home and I knew I had to do something.

"It's taken me to get to 40 to realise I have a responsibility as a woman and as a mother.

"I have a voice that people will listen to and I'm taking that responsibility very seriously. This is the beginning of an incredible journey for me."

Victoria, who was dressed in a navy suit, also told how she had worked with Aids organisations through her friend Sir Elton John.

"Elton John is a very dear friend of mine and David's and we've been patrons of the Elton John Aids Foundation for 20 years so I have been working a lot with lots of Aids charities," she explained.

The Rocketman singer's Aids foundation later tweeted: "Congratulations to our patron @victoriabeckham on becoming a @UNAIDS International Goodwill Ambassador."

Victoria also tweeted about being named a Goodwill Ambassador, saying: "As a woman & a mother I want to make change happen and support the @UNAIDS vision x vb."

The star was expected to jet back home after her speech for the opening of her first UK store.

Meanwhile, her husband David was holding down the fort, and was on hand to welcome fans at the three-storey shop in trendy Dover Street, Mayfair.