Tsvangirai was flown to neighbouring Botswana on Saturday to recover from the accident and to undergo another medical check-up, but is expected to return to Harare late on Monday, the official, who asked not to be named, told Reuters.
"The arrangement is that Mrs Tsvangirai will be buried on Wednesday in her rural home of Buhera," he said. A procession commemorating her would be held in Harare on Tuesday.
Tsvangirai, who left hospital in the capital on Saturday, has suffered head and neck wounds, but is in stable condition, other officials said.
Police have launched an investigation into the accident, which took place on Friday on a potholed road south of Harare.
Tsvangirai's MDC said they would conduct their own probe to see whether foul play was involved. The party said the crash could have been avoided if proper security had been in place.
The truck that collided with Tsvangirai's car belongs to the United States Development Agency and was carrying British and US aid. The British government said it believed the crash to be a "genuine accident", according to media reports.
The prime minister and his arch rival, President Robert Mugabe, formed a power-sharing government in February after months of negotiations to try to end a political and economic crisis that has brought Zimbabwe to ruin.
Tsvangirai, who turns 57 on Tuesday, had six children with Susan, who was popular among MDC supporters, who would chant "mother, mother" when she appeared at rallies with her husband.
Susan, 50, avoided the spotlight but stood by Tsvangirai throughout his ordeals as Mugabe's most determined opponent.
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