"And the war veterans threatened to burn the vehicles with my people inside unless they got out of the vehicles and accompanied the police to a station nearby."
The government in Harare said that the diplomats had been addressing a gathering at the home of an opposition party activist.
Bright Matonga, the deputy information minister, said: "The British and American diplomats had gone to a house in Bindura where they addressed a gathering. There was commotion and police were called in."
"When police arrived they fled and then they were stopped at a roadblock on the way. When they refused to disembark following orders by the police, police then deflated the tyres of one of the vehicles."
Speaking later to Al Jazeera, Matonga said that the envoys had been "distributing opposition campaign material" and were "operating outside their diplomatic mandate".
Matonga said that the envoys were required to inform Zimbabwe's ministry of foreign affairs if they intended to travel over 40km outside the capital and that the envoys had failed to do so.
"We don't understand why they don't want to respect our laws," he said.
'Attempted get away'
A US press spokesperson at the embassy told Al Jazeera that the group was "carrying out normal diplomatic business, collecting evidence from victims of political violence, when they were stopped in Bindura, by the Zimbabwean police.
"The police officials tried to take the diplomats to jail - in contradiction of the Vienna convention on diplomatic immunity.
"The US diplomats rang the US embassy who told the officials to go back to Harare.
"One car made it back. As one of the others drove off they were chased by police who tried to drive them off the road. The car was eventually brought to a halt at a road block – and its tyres were slashed.
"They were then surrounded by military, war veterans and police.
"Another car with security people which headed their way was also stopped and a satellite phone was stolen."
A British government spokesman later said that all their envoys had been freed and were safe.
The UK foreign office had summoned the Zimbabwean ambassador in London to explain the events.
The US embassy said that their officials had been released after several hours.
Mark Weinburg, an embassy spokesman, said: "They have all been released and are on their way back to Harare."
The White House then demanded that the Zimbabwean government "explain its actions" and said it planned to raise the incident at the UN security council.
Haru Mutasa, Al Jazeera's correspondent in Harare, said that Zimbabwean opposition supporters have said that this could have been an intimidation tactic as the diplomats were in the rural area checking on those affected by recent political violence.
She said that the vehicles' tyres had been punctured by spike ramps rolled out at the road block.
Mutasa added that diplomats are generally required to gain permission from the Zimbabwean government to move around the country.
However, the US state department had said that the diplomats did inform Harare of their movements.