Zimbabwean students Monday embarked on a protest demanding the release of political prisoners Job Sikhala and Jacob Ngarivhume in the process registering dismay over clampdown of dissenting voices.

This follows the duo's conviction earlier this month.

Renowned author Tsitsi Dangarembga and CCC spokesperson Fadzayi Mahere were also convicted with the former successfully appealing at the High Court.

The convictions have raised fears of a major clampdown on government critics as the country marches towards general elections.

Zimbabwe National Students Union (ZINASU) initiated a campaign dubbed Black Monday protesting against political persecutions.

Under the campaign students are wearing black as a symbol of repression and muzzling of voices.

"It is after we have recognised that the voice of the voiceless is being silenced by the regime. The voice of the voiceless is being choked by the oppressors. Each and every Monday we are going to make sure that the regime and all those who are in authority receive our displeasure for the ongoing oppression and repression which is targeted on voices of Zimbabwe," said ZINASU spokesperson Lennon Mazuru.

Sikhala has been in pre-trial detention since June last year following his arrest after violence rocked Nyatsime over the murder of CCC activist Moreblessing Ali.

Efforts to secure bail by the firebrand legislator have hit a snag.

"Black Monday is a symbol of showing the world that we are still in the dark. There is a total blackout in Zimbabwe in terms of our freedom and rights. There is no freedom hence it is a total blackout.

"Our voice is the voice of the nation. Our voice is to conscientise those who do not know the direction and status quo of our nation. Our voice is a torch to those who are not seeing. We are aware that the regime is ready and waiting to thwart every action," added Mazuru.

Meanwhile the Harare High Court and Constitutional Court were among buildings that were painted with graffiti by unknown activists demanding the release of Sikhala.