Christina Aguilera and Sienna Miller leading American launch of Red Nose Day

Pop superstar Christina Aguilera and actress Sienna Miller have signed up to front the U.S. launch of annual British charity telethon Red Nose Day.

The ladies have pledged their support to the fundraising bash by posing for pictures wearing the initiative's signature red nose to promote the campaign, which aims to raise awareness and attract donations to aid those in extreme poverty.

Mad Men star Jon Hamm is also reportedly set to take part in the live event, with more names set to be announced in the run up to the three-hour telethon on 21 May (15) in New York City, according to Variety.com.

The charity drive will be a variety show of sorts, featuring stand-up comedy sketches, musical performances and appearances from a slew of celebrities.

American Sniper actress Miller, who has previously been involved in the longrunning U.K. event, tells UsMagazine.com, "Red Nose Day is almost like a national holiday in the U.K. It's a day of real excitement as everyone looks forward to it and the entire country gets involved in some way. I'm thrilled it's coming to the U.S.!"

The U.K.'s 2015 Red Nose Day telethon took place last Friday (13Mar15) and featured appearances from celebrities including Daniel Craig, Emma Watson and Orlando Bloom. The initiative has raised more than $1 billion to date for good causes in the U.K. and Africa.