US evangelical Christian groups have played a key role in fomenting a climate of hatred that has resulting in harsh new anti-gay laws in Uganda, according to a new documentary.

The new laws, signed by Ugandan president Yoweri Museveni last month, mean that homosexuals in the east African nation can be imprisoned for up to 14 years.

In God Loves Uganda, leading human rights campaigners claim that having lost the "culture wars" on US soil, conservative Christian groups instead turned their attentions to the developing world.

"The anti-homosexuality bill would never have come about without the involvement of American fundamentalist evangelicals," said director Roger Ross Williams.

Though under colonial laws some homosexual acts were illegal in Uganda, people were rarely prosecuted.

That changed in 2009, allege campaigners, when American Pastor Scott Lively gave a series of inflammatory talks, claiming that homosexuals aimed to "recruit" children and destroy the "marriage based society."

"[The idea] of a gay agenda, of recruiting people to homosexuality – that language wasn't used in Uganda pre-2009. [Lively] made my work very difficult and was conspiring with my legislators, but [to Ugandans] he was like God himself. People were worshipping him as if he was from heaven," Dr Frank Mugisha, director of the LGBT rights organisation, Sexual Minorities Uganda told the Independent on Sunday recently.

According to the film, after the 1979 death of dictator Idi Amin, who was a Muslim, US-based Christian groups spent millions proselytising and building churches and schools in Uganda.

Among them was Kansas City-based International House of Prayer, founded by Mike Bickle.

"Bickle was there on the ground on the day Amin fell… with a group of American Christian leaders, to take the country as a Christian nation," said Williams.

IHOP has been explicit about its anti-gay agenda, holding rally of 33,000 in 2008 in protest against plans to legalise gay marriage in California.

MP David Bahati, who proposed the recent Ugandan anti-gay bill, is the member of a secretive US evangelical group The Family, based in Washington DC, which also has links to president Musveni.

In charting the rise of homophobia in Uganda though, campaigner Reverend Kipya Kaoma points to Lively's sermons, which he covertly filmed, as a tipping point.

"He brought to Uganda this new narrative of the so-called 'international gay agenda'… You might think, 'Is he out of his mind?' But people believed him, [and] the narrative since 2009 has been about protecting children from homosexuals."

Lively, who claimed in his book The Pink Swastika that homosexuality caused Nazism, is being sued on behalf of Dr Mugisha by the US Centre for Constitutional Rights for fomenting the anti-gay discrimination.

In response to the allegations, he said: "I was invited to Uganda by Ugandans who were concerned by the transformations that were beginning to take place in their society… It's a very racist premise to suggest that a white evangelical pastor, just by the force of his rhetoric, could overpower the will and intelligence of an entire African country."