"The unlawful arrest and subsequent severe assault of photojournalist Tsvangirai Mukwazhi while in police custody on March 11, 2007, and that of Gift Phiri on April 1, 2007, behoves Zimbabwean journalists to be on high alert as they conduct their lawful and professional duties," MISA said in a statement.

"The traumatic events of the past two months should also serve as a harbinger of the unknown dangers that lie ahead for journalists and media workers, given that Mukwazhi’s whereabouts remained unknown until his subsequent appearance in court three days later on March 14, 2007."

Mukwazhi was arrested while covering a prayer meeting called by civic society organisations three weeks ago, when opposition Movement for Democratic Change (MDC) leaders were also detained. He was allegedly severely tortured while in police custody, despite having the requisite practicing certificate from the country’s media regulatory authority, the Media and Information Commission (MIC).

Phiri, an independent journalist who contributes to the British-based ’The Zimbabwean’ newspaper, was also arrested last week and severely tortured. He was held in custody for nearly a week before being released but was subsequently charged with practicing without a license and "writing falsehoods".

Last week, Edward Chikomba, a cameraman previously with the Zimbabwe Broadcasting Corporation, the state broadcaster, was abducted from his home in Harare and later found murdered, his body dumped by the roadside near Darwendale, a township about 60km north of the capital, Harare.

Many journalists believe Chikomba was murdered for allegedly transmitting the images of a bruised and battered Morgan Tsvangirai, leader of one of the factions of the main opposition party, Movement for Democratic Change (MDC), to the international media, a charge the police have strongly denied.

Police spokesperson Wayne Bvudzijena told IRIN the police sympathised with the Chikomba family and were still investigating the circumstances surrounding his abduction and murder.

The Zimbabwe Union of Journalists (ZUJ), which represents the interests of the majority of journalists, also expressed the fear that there was a deliberate government policy to harass and intimidate the media. ZUJ secretary-general Foster Dongozi told IRIN that the organisation condemned all forms of media harassment.

"We condemn in the strongest possible terms the abductions and torture of journalists in the past few weeks. More frightening is the murder of Chikomba, whose killers are yet to be brought to book," Dongozi said.

"We wonder if this is government policy to silence the independent media, and we have already engaged the minister of Information and Publicity to clarify the government position on the issue; journalists are worried and wonder who is going to be the next victim of such barbarism. We are also concerned about the continuing arrest and assault of accredited journalists in the country," he added.

Information and Publicity minister Sikhanyiso Ndlovu told IRIN that the pattern of harassment and intimidation seen in the past three weeks was not a reflection of government policy. "Which country would allow such lawlessness to prevail? It is not our policy, and we condemn all such acts." He said his ministry was also investigating the incidents.

He expressed confidence in the police, and suggested that opposition elements bent on tarnishing the image of the country could be responsible for the wave of assaults on the media.

A number of other foreign correspondents have either been arrested or threatened by government since the beginning of the year. In 2006, Reporters Without Borders, a media watchdog, ranked Zimbabwe at 140 out of 168 countries listed in its Press Freedom Index, just below Equatorial Guinea and Sudan.