"The arrest of Dushantha Basnayake, who is close to a political adversary of President Mahinda Rajapakse, looks above all like retaliation," RSF said in a statement.

"The fears of human rights organisations have unfortunately turned out to be well-founded: The anti-terror law is being misused to silence critics. We call on the Sri Lankan government to release Dushantha Basnayake," it said.

Dushantha Basnayake, aged 40 and the father of two children, is Sinhalese. The weekly Mawbima has a reputation for criticising the government and for condemning human rights abuses and corruption in Sri Lanka, RSF said.

The newspaper is owned by close ally of former Sri Lanka foreign minister Mangala Samaraweera who was sacked from the government together with two others earlier in February.

"Officers of the Terrorist investigation Division (TID) went to Basnayake's office at around 6pm and began questioning him," RSF said.

"After four hours of interrogation, the officers apparently received a call from a high ranking defence ministry official ordering them to put him under arrest."

A young Tamil journalist working for the paper, Munusamy Parameshawary, has been held by the TID under the anti-terror law since November 2006.

The newspaper offices have also been visited by tax inspectors, RSF said.

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