Zimbabwe's upcoming general elections will take place amid a crackdown by the state on human rights activists and opposition supporters, Amnesty International warned in a report released.

The London-based human rights group said in the 36-page report, Walk the Talk, that there is a "systematic clampdown" on free speech and the right to assemble.

While violence in the run-up to the July 31 poll has been lower than in previous election cycles, campaigners for a free vote are being jailed while their offices are raided by police and equipment confiscated.

Elections in 2008 descended into widespread violence largely targeting the opposition. Some 200 people were killed across the southern African nation, thousands were arrested and many tortured.

The security forces are still widely believed to be controlled by President Robert Mugabe's Zanu-PF party. The 89-year-old Mugabe, who has ruled Zimbabwe since independence in 1980, will again contend for the country's top office.

"The clampdown on the work of human rights defenders is a worrying indicator that government agencies remain actively hostile to civil society," said Noel Kututwa, Amnesty's Africa deputy programme director.

"Zimbabwe's security forces must respect and protect fundamental freedoms as the country prepares for a high-stakes election," said Kututwa.

Police officials deny allegations of being partisan.

Andrew Phiri, the national police spokesman, told dpa: "We do not condone any member of us violating any human rights."

He added: "We would investigate that if we have a name, a date and place where the violations took place. But in this report there is nothing tangible."

The report details several specific cases of crackdowns. Since November 2012, at least five police raids of offices of non-government organizations have been conducted and dozens of human rights defenders detained, often in what appear to be violations of local and international law.

In one recent instance, members of the Youth Initiative for Democracy in Zimbabwe were harassed for simply "conducting voter education without authority from Zimbabwe Electoral Commission." They were detained and a trial is expected to start in August.

Though the prosecution of human rights defenders does not necessarily result in convictions, they effectively paralyse the organizations through regular court appearances of the leaders and draining their finances.

Moreover, the arrests generate a climate of fear, especially given the history of political violence in the country.

"The stakes are high in this election and the run-up to it cannot simply be treated as business as usual, either by stakeholders in Zimbabwe or by the international community," said Kututwa.

Zimbabwe recently passed a new constitution, paving the way for elections this year. Amnesty said the government "must walk the talk and honour the commitments enshrined in it and protect the fundamental freedoms of its citizens."Authors: Columbus Mavhunga, Shabtai Gold