Sri Lankan authorities have blocked several news websites, including a portal run by the opposition UNP, days after citing complaints that top public officials including the president were being targeted with 'defamatory' reports.

The move was criticised by the main opposition United National Party that termed it undemocratic.

The Sri Lankan ministry of media had on Saturday ordered news websites publishing reports about Sri Lanka to obtain accreditation from the information department.

Over the last two days several websites have been blocked including Lankawaynews.com, which is said to be the UNP's official website.

The website was running on a trial basis and was to be launched this month, the head of the UNP's media unit, parliamentarian Mangala Samaraweera was quoted as saying by Colombo Page.

Samaraweera said politicians were public figures whose actions come under close scrutiny and that his party would continue to campaign against such "undemocratic moves".

The Ministry of Mass Media and Information had said it was "receiving many complaints from various individuals who have been subjected to defamation and character assassination by certain reports published in several websites".

The statement added that the President, ministers, and senior public officials have come under attacks and deliberate character assassination campaigns in such reports.

Sri Lanka had already blocked anti-government websites like Lankanewsweb, Lankaenews and TamilNet.

Human rights groups and media freedom watchdogs have criticised the Sri Lankan government for stifling freedoms.

The US embassy had this week said that freedom of expression, including unfettered access to Internet news websites, was a basic right which must be respected by Sri Lankan authorities.

Secretary to the Ministry of Media and Information W B Ganegala said that certain websites are continuously publishing reports falsely accusing the President, MPs and Ministers as well as high ranking government officials in a manner tarnishing their reputations, according to Sri Lanka Braodcasting Corporation.

He said the ministry was "compelled" to take action against such websites and is in the process of accumulating their addresses, apparatus and information regarding their staff.