The raid followed provincial meetings held at the offices by party members earlier in the day in preparation for their forthcoming congress.
Zimbabwean police raided late Sunday the headquarters of the Movement for Democratic Change formation of Prime Minister Morgan Tsvangirai and arrested 10 activists, among them three staff members and seven youths.
Those arrested were still in custody on Monday though no charges had officially been laid, the party said in a statement.
The raid followed provincial meetings at the party offices by members earlier in the day in preparation for a forthcoming congress. Police spokesman Wayne Bvudzijena could not be reached for comment.
Party spokesman Nelson Chamisa told VOA Studio 7 reporter Jonga Kandemiiri that the police raid was part of an ongoing crackdown by President Robert Mugabe's ZANU-PF party against MDC supporters.
Meanwhile, the MDC formation led by Welshman Ncube has instructed its lawyers to file contempt of court charges against its former president and Deputy Prime Minister Arthur Mutambara for continuing to represent the party at meetings by the principals despite a court order barring him from representing it until a leadership dispute is resolved.
Mutambara is challenging the court interdict. Senior party officials confirmed Ncube will be instructing lawyer Josphat Tshuma on the matter, but Tshuma said he was yet to receive the instructions.
MDC Spokesman for the Bulawayo Province Edwin Ndlovu told VOA Studio 7 reporter Sithandekile Mhlanga that his party was also seeking contempt of court charges against President Mugabe and Mr. Tsvangirai, who represent ZANU-PF and the MDC-T respectively in the principals meetings, for allowing Mutambara to attend the discussions.