KUALA LUMPUR, Aug 6 (Reuters) - Malaysia is considering the establishment of an Internet filter, similar to China’s abandoned “Green Dam” project, a source familiar with the process told Reuters on Thursday.

News of the proposal emerged within days of police arresting nearly 600 opposition supporters at a weekend rally denouncing a government that has ruled this Southeast Asian country for 51 years.

A vibrant Internet culture has contributed to political challenges facing the government, which tightly controls mainstream media and has used sedition laws and imprisonment without trial to prosecute a blogger.

“They (the government) are looking to tweak the technical and legal details of implementing this Internet filter, setting the stage for its implementation late this year or next year,” said the source, who declined to be identified.

No one from the government was available for comment.

“Submissions are to be handed in by July or August. About four groups have tendered for this project,” the source said.

China last month delayed the introduction of its proposed Green Dam internet filter which authorities said sought to stamp out pornography. Opponents of censorship, industry groups and the United States said the project was intrusive and unfair.

Malaysia plans to double home Internet penetration to 50 percent by the end of next year with a new broadband project.

New Information, Communication and Culture Minister Rais Yatim, whose ministry issued the tender, also plans to secure control over the content and monitoring division of Malaysia’s Internet regulator, a second source said.

“The minister wants to focus more on enforcement in the coming year,” the source said.

Malaysia, with a population of 27 million, attracted foreign technology companies such as Microsoft Corp MSFT.O and Cisco Systems CSCO.O to invest and guaranteed that the government would not impose controls on the Internet.

Rais said last month that wider broadband access required more regulation.

“With the good comes the bad through the broadband over the Internet,” he said. “We will introduce certain measures to overcome the bad.” (Additional reporting by Royce Cheah, editing by Ron Popeski)