HARARE, Zimbabwe - Prime Minister Morgan Tsvangirai left the hospital bandaged and mourning his wife yesterday after a car crash that his supporters blamed partly on insufficient security provided by President Robert Mugabe.

Tsvangirai's Movement for Democratic Change called for an investigation into the collision with a truck carrying U.S. aid, but cautioned against concluding that it was the latest assassination attempt against the longtime opposition leader.

Friday's crash nonetheless "could have been avoided" if Tsvangirai had the kind of motorcade that usually travels with Mugabe, said Tendai Biti, the country's new finance minister and Tsvangirai's No. 2 in the party. An MDC official who was traveling with Tsvangirai said the premier's Toyota Land Cruiser was accompanied by three vehicles with MDC security and one with Mugabe's agents, but not the kind of motorcade with dozens of cars and motorcycles that usually transports the president.

The official spoke on condition of anonymity because of the sensitivity of the issue.

Tsvangirai was headed to a weekend rally in his home region when the accident occurred. State television said the truck swerved on an uneven and notoriously dangerous single-lane stretch of road on the outskirts of the capital, Harare. Tsvangirai's spokesman said the car carrying the prime minister, his wife, his driver, and his bodyguard had sideswiped the truck and rolled at least three times.

Susan Tsvangirai, 50, was pronounced dead soon after arrival at a clinic about 25 miles from Harare, said Ian Makone, a secretary in the prime minister's office and a member of his party. The state-run Herald newspaper reported that the driver and bodyguard were injured. Tsvangirai's brother, Casper, told reporters yesterday that the bodyguard had gone home and that the driver remained hospitalized but was not seriously injured.

Mugabe sent the prime minister's family a message that called Susan Tsvangirai's death a "tragedy that has fallen on our nation at a time of great hope for our country," state radio reported. The president also said the nation was praying that the prime minister's recovery "be swift and complete."

Biti said there should be a probe of the collision and a review of Tsvangirai's security.

"We cannot talk of foul play . . . until it has been proved what has really transpired," Biti said. He did not say whether his party had requested a larger convoy for Tsvangirai at any time before the crash.

Police Superintendent Andrew Phiri told the Herald that the truck may have struck an object on the road before it veered. The Herald said the driver and occupants of the truck were taken to a police station, but it was not clear whether they had been arrested.

A U.S. Embassy official, speaking on condition of anonymity because the official spokesman was unavailable, said yesterday that the truck involved was transporting AIDS medicine donated by the U.S. government. It was driven by a Zimbabwean hired by the United States.