Britain is threatening to revoke financial aid to poor African countries that don't support gay rights.
The Daily Mail Online reported that British Prime Minister David Cameron is trying to take a "gay rights crusade to the world."
Britain has already slashed about $30 million in aid from Malawi after that African nation sentenced two homosexuals to 14 years of hard labor.
The British government is also threatening to punish Ghana and Uganda for outlawing homosexuality.
Cameron also wants gay couples to enjoy the same rights as Britain's heterosexual couples.
During remarks at a party conference last week, the prime minister said as a Conservative, he supports same-sex marriage.
"Conservatives believe in the ties that bind us; that society is stronger when we make vows to each other and support each other," he told fellow Conservatives.
"So I don't support gay marriage despite being a Conservative. I support gay marriage because I am a Conservative," he said.
Gay couples in Britain enjoy most of the same legal rights as heterosexual couples, but the term "marriage" is not used.
Some church leaders and conservative parliamentarians have opposed Cameron's plan to legalize same-sex marriage in Britain.