Harare - Zimbabwe police raided the offices of a leading election monitoring group on Tuesday in the latest of what activists fear is a deliberate move by authorities to harass them ahead of a referendum on the constitution.

Police forcibly entered the offices of the Zimbabwe Election Support Network (ZESN) by breaking part of the perimeter wall and confiscated documents, a human rights lawyer said.

No arrests were made.

“They had a search warrant to search for subversive material, documents, gadgets, recordings and to look for illegal immigrants,” Zimbabwe Lawyers for Human Rights spokesperson Kumbirai Mafunda told reporters.

Police have in recent weeks targeted non-governmental organisations as the country readies for a crucial constitutional referendum on March 16.

With the referendum on the horizon, political tensions are building and activists are increasingly being targeted.

The Crisis in Zimbabwe Coalition said the raids appear “to be a calculated state-sponsored move to inculcate fear in CSOs doing election-related work”.

Authorities have in the past threatened to revoke licences for groups deemed to be opposed to Mugabe's policies.

Tsvangirai's Movement for Democratic Change party has urged the police to stop harassing rights activists and party supporters. - Sapa-AFP