It has been attacked many times in its short life, most notably by a former aide to Robert F Kennedy and the editor of Encyclopaedia Britannica. But now the online reference site Wikipedia has a new foe: evangelical Christians.

A website founded by US religious activists aims to counter what they claim is "liberal bias" on Wikipedia, the open encyclopedia which has become one of the most popular sites on the web. The founders of Conservapedia.com say their site offers a "much-needed alternative" to Wikipedia, which they say is "increasingly anti-Christian and anti-American".

Although entries on Wikipedia are open for anyone to edit, conservative campaigners say they are unable to make changes to articles on the site because of inherent bias by its global team of volunteer editors. Instead they have chosen to build a clone which they hope will promote Christian values.

"I've tried editing Wikipedia, and found that the biased editors who dominate it censor or change facts to suit their views," Andy Schlafly, the founder of Conservapedia, told the Guardian. "In one case my factual edits were removed within 60 seconds - so editing Wikipedia is no longer a viable approach."

Among his criticisms listed on Conservapedia, Mr Schlafly explains how many Wikipedia articles often use British spelling instead of American English and says that it "refuses" to give enough credit to Christianity for the Renaissance. "Facts against the theory of evolution are almost immediately censored," he continues.

Mr Schlafly, a lawyer by day, is the son of a prominent American conservative, Phyllis Schlafly, renowned for her opposition to feminism and the Equal Rights Amendment. He says Conservapedia was created last November as a project for home-schooled children - and believes it could eventually become a reference for teachers in the US. "It is rapidly becoming one of the largest and most reliable online educational resources of its kind," he said.

Wikipedia has come in for criticism for its open approach, notably from Dale Hoiberg, the editor-in-chief of Encyclopaedia Britannica. Mr Hoiberg disputed a survey in the scientific journal Nature which found that the website was just as accurate as its venerable counterpart. Meanwhile, a Tennessee journalist, John Seigenthaler, attacked the site for suggesting he had been accused of involvement in the assassinations of both John and Bobby Kennedy in the 1960s.

The arrival of Conservapedia has been met with derision by much of the internet community. But Jimmy Wales, the co-founder of Wikipedia, said he was not upset by the rightwing site's claims.

"Free culture knows no bounds," he said. "We welcome the reuse of our work to build variants. That's directly in line with our mission."

How they compare:

Dinosaurs

Wikipedia, logo above

"Vertebrate animals that dominated terrestrial ecosystems for over 160m years, first appearing approximately 230m years ago."

Conservapedia

"They are mentioned in numerous places throughout the Good Book. For example, the behemoth in Job and the leviathan in Isaiah are almost certainly references to dinosaurs."

US Democratic party

Wikipedia

"The party advocates civil liberties, social freedoms, equal rights, equal opportunity, fiscal responsibility, and a free enterprise system tempered by government intervention."

Conservapedia "The Democrat voting record reveals a true agenda of cowering to terrorism, treasonous anti-Americanism, and contempt for America's founding principles."