Harare  - The heads of the umbrella organization for all of Zimbabwe's non-governmental organizations were arrested on Sunday amid worsening signs of the disintegration of the country's fragile coalition government.

Cephas Zinumhwe, chief executive of the National Association of Non-Governmental Organisations (NANGO), and its chairperson, Dadirai Chikwengo, were arrested at the small airport in the northern resort town of Victoria Falls after a NANGO meeting, spokesman Farai Ngirande said.

Ngirande said they were accused of "holding a public political meeting without approval" - a claim NANGO rejects - and were held by police overnight.

The two were due to appear in court in Victoria Falls later Monday, while President Robert Mugabe and Prime Minister Morgan Tsvangirai were scheduled to meet in Harare to discuss the paralysis in their eight-month-old unity government.

Ten days ago, Tsvangirai's Movement for Democratic Change (MDC) announced a partial withdrawal from the government, saying Mugabe's Zanu-PF was "a dishonest and unreliable partner." The party is boycotting cabinet meetings but MDC ministers are continuing to run their portfolios.

The NANGO arrests are part of a fresh security clampdown on the MDC and rights activists, which some see as a reprisal for the MDC boycott.

NANGO represents a broad alliance of human rights, welfare, gender and poverty relief organizations.

Early Saturday a crowd of police, claiming to be searching for weapons, ransacked a residence owned by the MDC and assaulted the caretaker and workers.

Last week, Tsvangirai took his dispute with Mugabe to Zimbabwe's neighbours in the region, meeting with the leaders of South Africa, Mozambique, Democratic Republic of Congo and Angola to seek support for the MDC's position.

Mugabe has, however, maintained a defiant stance, telling state media at the weekend his party had fulfilled its side of the power-sharing deal and would not be pressured by the MDC into relinquishing more power.

Mugabe was pushed by the Southern African Development Community into negotiations with the MDC last year after claiming power following a violent presidential election that was universally condemned as a sham.

Tsvangirai accuses Mugabe of ignoring a raft of obligations in terms of the power-sharing agreement, including requirements to implement human rights reforms and share power equitably among the two parties.(dpa)