Zimbabweans have held a memorial for the wife of Morgan Tsvangirai, the country's prime minister, in the capital Harare.

Susan Tsvangirai was killed when a foreign aid lorry collided with the car she and her husband were travelling in on a country road outside Harare last week.

Robert Mugabe, the long-standing president of Zimbabwe, joined thousands of mourners at the memorial ceremony on Tuesday, and wished the prime minister strength for what he called the "nation-building work" that lay ahead.

"This is a difficult moment for our colleague. He has lost a partner and we must all rally to support him and lessen his burden ... this is the hand of God," Mugabe said.

He called on Zimbabweans to end violence and support his old rival in rebuilding the country.

"That's what [Susan] Tsvangirai would have wanted, for us to co-exist peacefully," he said.

"We have just started a new life after years of fighting each other and insulting each other. We have said let's give peace and harmony a chance and work together."

'Peace and harmony'

Mugabe and Tsvangirai entered into a unity government in February after disputed elections in early 2008 had led to an outbreak of violence and almost a year of political deadlock.

That government is now faced with the task of tackling a financial crisis that has led to food shortages and the world's highest inflation rate, as well as a cholera epidemic partially blamed on the collapse of the country's health and sanitation systems.

The past political tensions had prompted speculation that Friday's car crash may have been an assassination attempt, but speaking on Monday, Tsvangirai said "if there was any foul play, it was one in a thousand".

"It was an accident and unfortunately it took her [Susan's] life," he said.

A burial ceremony for Susan Tsvangirai is planned on Wednesday in her hometown of Buhera - where she and her husband had been headed on the day of the accident.