Saudi Arabia has lashed a liberal blogger 50 times in public, despite widespread international outrage and calls for clemency from human right groups.

Hillel Neuer, Executive Director of UN Watch, said on twitter that blogger and activist, Raif Badawi, was lashed outside a mosque in the Red Sea coastal city of Jeddah on Friday.

Badawi is due to undergo 50 lashes every week after Friday prayers, which will continue for 20 weeks until his punishment is complete.

Amnesty International says Badawi, who started the "Free Saudi Liberals" website, was sentenced to 10 years in prison and 1,000 lashes on charges related to accusations he insulted Islam on the online forum.

He was also ordered by Jeddah's Criminal Court to pay a fine of $266,000.

"It is horrifying to think that such a vicious and cruel punishment should be imposed on someone who is guilty of nothing more than daring to create a public forum for discussion and peacefully exercising the right to freedom of expression," Philip Luther, Amnesty's Middle East and North Africa Director, said.

"Saudi Arabian authorities must immediately halt all plans to carry out this brutal sentence," he said.

The United States had also appealed to Saudi Arabia to cancel the sentence.

State Department spokeswoman, Jen Psaki, said the US was "greatly concerned." She called the 1,000 lashes an "inhumane" response to someone exercising his right to freedom of expression and religion.

"The United States government calls on Saudi authorities to cancel this brutal punishment and to review Badawi's case and sentence," Psaki said.

Around 14,000 people have signed an online petition calling on Saudi's King Abdullah to pardon Badawi.

Rights groups and activists say his case is part of a wider clampdown on dissent throughout the kingdom.

Source: Al Jazeera and agencies