An anti-gay US pastor has warned his flock against drinking Starbucks coffee, claiming it is flavoured with the "semen of sodomites".

Controversial New York City pastor James David Manning's attack against the coffee giant came after coffee-sipping LGBT activists protested outside his ATLAH Worldwide Missionary church in Harlem.

"They had a big bucket of Starbucks coffee," the pastor, who once infamously claimed US President Barack Obama was a "homo", said in his traditional online broadcast - the Manning Report.

"The thing that I was not aware of is that... what Starbucks was doing, is they were taking specimens of male semen, and they were putting it in the blends of their lattes".

Manning's claim was based on a fake report by satirical website Huzlers, which the pastor didn't name, quoting instead an article debunking the story by The Inquisitr, which he probably didn't read.

"It's the absolute truth. They're using male semen, and putting it into the blends of coffees that they sell," he said.

"My suspicion is that they're getting their semen from sodomites," he continued. "Semen flavours up the coffee, and it makes you think that you're having a good time drinking that cup of latte with the semen in it".

It was the second time in a week that Manning made appalling homophobic claims targeting Starbucks for its gay-friendly stance.

Last week, he said the coffee chain was "ground zero for Ebola" because "upscale sodomites" went there.

"They sit there with their computers and it's a meeting place, they exchange a lot of body fluids, hands shaken and contact," he said.

Sparked by Starbucks' new ad campaign featuring two drag queens, Manning's rant triggered widespread outrage and a demonstration by LGBT activists outside his church.

"They said this church is a hate church and I'm a hate preacher," he said.

Starbucks has advocated in favour of gay rights in the past, publicly endorsing plans for a same-sex-marriage legislation in the state of Washington in 2012.