U.S. and British diplomats were attacked Thursday as they tried to investigate political violence in Zimbabwe and a U.S. Embassy employee was beaten, American officials said.
The 12 members of the group were released about six hours after being stopped at a roadblock just north of Harare.
The White House demanded that Zimbabwe's government "explain its actions." Secretary of State Condoleezza Rice condemned the detention as "outrageous behavior."
"This is a regime that is very much out of step with international norms," she said.
State Department spokesman Sean McCormack said the U.S. planned to raise the incident in the U.N. Security Council and would seek out the Zimbabwean delegation at a U.N.-organized food aid conference in Rome to protest.
A spokesman for the U.K. government said that none of the British diplomats were harmed. Britain also summoned Zimbabwe's ambassador to discuss the detentions.
'Beaten and thrown into a ditch'
U.S. Ambassador James McGee, who was not with the convoy, told NBC News by telephone that Zimbabwean police and so-called war veterans, a group of fiercely loyal and often violent supporters of President Robert Mugabe, were responsible for the incident.
He told CNN that five Americans, four Britons and three Zimbabweans were in the three-car convoy.
He accused the police of slashing the tires of a vehicle after stopping the convoy.
"The driver was dragged from his car, beaten and thrown into a ditch," he told NBC, saying that the man was not seriously injured.
"At one point we had a group of so called war veterans arrive on the scene," McGee said. "These folks walked up to our vehicles and threatened to burn the people inside the vehicles unless they exited and accompanied the police to a nearby police station."
The BBC reported the victim was a Zimbabwean driver working with a U.S. security official.
He denied suggestions by Zimbabawean officials that the U.S. diplomats had attended an opposition rally. He said they were investigating reports of violence against members of the opposition.
British Foreign Secretary David Miliband said none of the British diplomats was harmed.
"This is a window into the lives of ordinary Zimbabweans," Miliband said. "We have to be concerned obviously about British staff, but we also have to be concerned that intimidation does not become the order of the day" ahead of the presidential runoff.
Order of intimidation
McGee blamed the incident on Mugabe's government.
He told CNN he believed the orders of intimidation are "coming directly from the top."
"Zimbabwe has become a lawless country," McGee added. "The government is trying to intimidate its own people into voting what they consider the correct way, and now what they're trying to do is intimidate diplomats" from traveling into the countryside.
The opposition and rights groups have accused Mugabe of orchestrating violence and intimidation in the run-up to a June 27 presidential runoff.
Police spokesman Wayne Bvudzijena denied security agents had threatened the diplomats, saying instead that police were trying to rescue them from a threatening mob.
"It's unfortunate when diplomats behave like criminals and distort information," Bvudzijena said. "It is a very sad situation."
Previous incident
In mid-May, McGee had led a similar convoy that was stopped at a police roadblock. Police eventually let the convoy through, and a patrol car escorted them back to the U.S. Embassy before disappearing.
At one point during the May incident, a police officer threatened to beat one of McGee's senior aides. The officer got into his car and lurched toward McGee after he had demanded the officer's name. The car made contact with McGee's shins, but he was not injured.
Meanwhile, Zimbabwe's opposition presidential candidate resumed campaigning Thursday, the morning after he spent nine hours in police detention near the country's second main city, his party said.
Morgan Tsvangirai said in a statement that the hours he spent in a Bulawayo police station after being stopped at a roadblock while campaigning demonstrate the lengths to which Mugabe was prepared to go to "try and steal" the runoff.
But police spokesman Bvudzijena said police merely wanted to establish that one of the vehicles in Tsvangirai's convoy was properly registered. He said police had asked only the driver to accompany them from the roadblock to the station, but others in the party insisted on coming and waiting while the documents were reviewed.
Rights activists also said that alleged Mugabe supporters petrol-bombed an office of Tsvangirai's Movement for Democratic Change in the southern province of Masvingo on Wednesday, killing at least two party officials.
Rice indicated she will keep U.S. diplomats in Zimbabwe rather than recall them in retaliation for Thursday's incident. McGee told NBC that U.S. diplomats would not be intimidated.
"We need to ensure the world knows what's happening here in Zimbabwe," he said.