HARARE (Reuters) - Zimbabwean police detained U.S. and British diplomats on Thursday, slashing the tyres of their cars after they visited victims of political violence ahead of a presidential election run-off, the U.S. embassy said.
The U.S. ambassador blamed the attack on President Robert Mugabe's government.
Former colonial power Britain and the United States accuse Mugabe of a campaign of violence and intimidation against supporters of opposition leader Morgan Tsvangirai in the run-up to the vote.
The attack took place in Bindura, 80 km (50 miles) north of Harare, a U.S. embassy spokesman said.
"Police put up a roadblock, stopped the vehicles, slashed the tires, reached in and grabbed telephones from my personnel, and the war veterans (Mugabe's supporters) threatened to burn the vehicles with my people inside unless they got out and accompanied police to a station nearby," U.S. Ambassador James McGee said in an interview on CNN.
"We do believe this is coming directly from the top," he said.
Tsvangirai beat Mugabe in a March 29 presidential election but failed to win enough votes to avoid a second round.
The opposition says 65 people have been killed since the first round of voting by supporters of Mugabe's ruling ZANU-PF party who want to extend his 28-year rule. Mugabe blames the opposition for the violence.
Tsvangirai was detained for nine hours on Wednesday but continued his campaign on Thursday.
South Africa said it planned to begin sending election observers to Zimbabwe this week as part of a larger mission sent by the Southern African Development Community, adding that it was essential that the election be fair and transparent.
Simba Makoni, the ruling party defector who came third in the first round called on Thursday for the run-off to be scrapped to prevent further bloodshed.
Makoni won over 8 percent and those who voted for him could be crucial in deciding the contest.
In an indicator of Zimbabwe's rapid economic decline, its dollar currency plunged to a new low of between 995 million and 1.45 billion to the greenback on Thursday from an average 700 million at the beginning of the week.
(Additional reporting by MacDonald Dzirutwe in Harare and Paul Simao in Johannesburg; Writing by Marius Bosch; Editing by Matthew Tostevin)
