Nelson Chamisa, chief MDC spokesman, said deputy party leader Thokozani Khupe and MDC chairman Lovemore Moyo were also being held with Tsvangirai.

  

"It's the whole entourage of the president, including his security personnel and other senior party officials," he said.

 

News of Tsvangirai's detention brought swift condemnation from the US state  department with a spokesman calling it a "deeply disturbing  development".

  

"We would call for his immediate release and we are sure that all others who have an interest in seeing free and fair elections take place in Zimbabwe ... will call for the same," Sean McCormack said.

 
George Sibotshiwe, Tsvangirai's spokesman, said the group were being held at the police station in Lupane, north of the city of Bulawayo.
 
"It's not an arrest but illegal detention. It appears they want to disrupt our campaign programme," he said.
 
Tsvangirai has been detained since 1000 GMT. Police searched all vehicles and inspected documents, the MDC said.
 
Presidential run-off
 
Tsvangirai has been trying to rally support as he prepares to face Robert Mugabe, Zimbabwe's president, in the June 27 presidential run-off election.
 
Both Mugabe and Tsvangirai say they are confident of victory.
 
Looking ahead to a post-election transition, Tsvangirai said his government will reform the civil service, judiciary and security forces, but he pledged not to purge pro-Mugabe officials.
 
After elections on March 29, Mugabe's Zanu-PF party lost its majority in parliament for the first time in 28 years and Tsvangirai won the presidential election, but without the overall majority required for an outright win.
 
A delay in the release of election results triggered a wave of violence across the country, particularly in rural areas.
 
The MDC says that since March more than 50 people have been killed by elements of Zanu-PF in election-related attacks.

 

Charities banned

 

Zimbabwe has ordered aid groups Save the Children UK, CARE International and ADRA to stop work in the country immediately, the director of a national NGO association said on Wednesday.

  

The government has sent letters to the groups issuing the orders, Cephas Zinhumwe, chief executive of the National Association of Non-Governmental Organisations (NANGO), said.

  

Zinhumwe said he had met with the three organisations he named as being sent the letters.

  

NANGO had earlier issued a statement saying several unnamed organisations had been ordered to cease operations over accusations that they campaigned for the opposition ahead of an upcoming  presidential run-off election.

  

The association said it was "deeply disturbed by the fact that  several NGOs, including those in the humanitarian sector, have been  banned from delivering humanitarian assistance and other crucial  services they are registered to deliver."