The Huffington Post launched a British edition on Wednesday, in the first expansion outside North America for its news and opinion website.
The Huffington Post UK has hired a small team of full-time journalists to produce the website as it seeks to push into international markets following its acquisition in February by Internet company AOL for $315 million (218 million euros).
The site, www.huffingtonpost.co.uk, has enlisted high-profile contributors from the world of politics and entertainment, including former British prime minister Tony Blair and comedian Ricky Gervais.
"I am delighted to be in London today for the first Huffington Post launch outside of North America," said a blog post from founder Arianna Huffington, who is now president and editor-in-chief of AOL Huffington Post Media Group.
"We are arriving here in the midst of a rich and thriving media culture marked by great innovation."
A Canadian edition of the site was launched in May and a spokeswoman said there were plans to expand into France and Russia although there were no firm launch dates as yet.
The Huffington Post's blog-led model, offering a lively mix of news, entertainment and opinion submitted by academics, entertainment figures and politicians, has proved immensely popular.
The US site, which was set up in 2005, attracted 36 million unique users last month, a spokesman said.