Harare - Supporters of President Robert Mugabe disrupted the first milestone event in the drafting of a new constitution on Monday, forcing riot police to drive thousands of delegates out of the conference.

Dozens of youth supporters of the elderly president, who had been bussed in to the constitutional stakeholders conference in Harare from rural areas, poured water on ministers from Prime Minister Morgan Tsvangirai's Movement for Democratic Change (MDC) party and drowned out an MDC speaker with songs.

About 100 members of Mugabe's Zanu-PF party prevented parliament speaker Lovemore Moyo of Tsvangirai's MDC from delivering the opening address.

The protestors accused the MDC of attempting to write a constitution that denies Zimbabweans the right to their land, referring to the MDC's disapproval of Mugabe supporters seizing white-owned farms.

Others blamed Tsvangirai for failing to persuade the European Union and the United States to lift targeted sanctions against Mugabe and scores of Zanu-PF members and companies linked to the party.

"The whole process is flawed. Tsvangirai must lift the sanctions first," one of the protestors clad in a torn, sleeveless Zanu-PF T-shirt, said.

Mugabe blames the sanctions for his country's economic ruin but most analysts blame his ruinous policies.

Most delegates left the conference when riot police failed to rein in the protestors.

But MDC ministers and members of parliament remained seated despite being soaked in water.

"That was done by those who do not want the constitutional process to go ahead," said Tendai Biti, MDC secretary-general and finance minister in the coalition government formed by Mugabe and Tsvangirai.

Biti said he believed the protest was orchestrated. But Mugabe's nephew, Patrick Zhuwayo, a Zanu-PF MP insisted: "It was spontaneous."

Under the agreement that Mugabe and Tsvangirai signed last September and implemented in February, Zimbabwe is supposed to write a new constitution by July 2010. The current constitution gives Mugabe sweeping executive powers. (dpa)