UK party leaders back global gay rights campaign
David Cameron, Nick Clegg and Ed Miliband have given their backing to a new organisation which aims to promote gay rights around the world.
Kaleidoscope will campaign against homophobic prejudice and violence, particularly in Africa and the Middle East, where punishments for homosexuality can be severe.
The prime minister said such treatment was "simply appalling".
Commons Speaker John Bercow will host a reception to launch the campaign.
Mr Bercow is also Kaleidoscope's honorary president.
At present, homosexuality is illegal in 76 countries, including 38 within the Commonwealth. At least five countries - the Yemen, Saudi Arabia, Iran, Mauritania and Sudan - have used the death penalty against gay people.
One of Kaleidoscope's founders, Bisi Alimi, said: "I was the first person from Nigeria to openly declare my sexuality on national television. As a result I was attacked, tied up and beaten in my own home in Lagos. I was forced to leave my country.
"My dream is that others like me will be free to stay and be happy surrounded by the love of their friends and families.
"Kaleidoscope can make a real difference, so I hope people will support us so that maybe one day my dream will come true."
The prime minister said he wanted Britain to be "a global beacon for reform".
"In some countries, it's simply appalling how people can be treated - how their rights are trampled on and the prejudices, and even violence, they suffer," he added.
Labour Leader Ed Miliband said: "I am proud to offer my support to Kaleidoscope as it seeks to protect LGBT [lesbian, gay, bisexual, transgender] people from prejudice and persecution across the world."
Deputy Prime Minister and Liberal Democrat leader Nick Clegg said of the new charity: "We share your belief that global problems have grassroots, local solutions."
As well as politicians, the campaign is backed by other high-profile figures, including singers Elton John and George Michael, and journalist and former Conservative MP Matthew Parris.
Broadcaster Paul Gambaccini, who has made a donation to Kaleidoscope, said: "It is time for those of us who enjoy our rights in the UK to support movements for dignity and decency wherever they are located."