Ethiopian police have rejected charges that recent arrests of several high-profile government critics were politically motivated.

Deputy federal police commissioner Demesash Woldemikael said Friday the detentions of journalists and opposition leaders are based on accusation they had contact with groups that are outlawed under the new anti-terrorism law and were planning terrorist attacks. He did not elaborate.

An Ethiopian counter-terrorism task force recently arrested several government critics, including journalist Eskinder Nega and a member of the opposition Unity and Justice for Democracy party, Andualem Aragie.

UDJ leader and former Ethiopian President Negasso Gidada said the arrests of dissidents will strengthen the opposition in its peaceful struggle against Prime Minister Meles Zenawi's 20-year rule.

UDJ general secretary Asrat Tassie expressed skepticism about the existence of any terrorist threat, saying the detentions appear to be an attempt by the country's ruling party to stem growing unrest.

The arrests have come under strong criticism from human rights and press freedom groups. The New York-based Committee to Protect Journalist said Friday that a sixth journalist has been arrested under the new anti-terror law.

Human Rights Watch called on the Ethiopian government to ends it growing crackdown on opposition politicians and activists.