HARARE, ZIMBABWE - Police confronted diplomats seeking to investigate allegations of torture Tuesday, halting their convoy at a roadblock on the edge of the capital. One officer threatened to hit the U.S. ambassador with his car.

The U.S. ambassador, James McGee, was not hurt. Police eventually let the convoy through, and a patrol car escorted them back to the U.S. Embassy before disappearing.

Tensions have been escalating in Zimbabwe since the March 29 parliamentary and presidential elections.

Opposition leader Morgan Tsvangirai claims he won the presidential race outright, but official results released weeks after the poll showed he did not win enough votes to avoid a second round against President Robert Mugabe.

The diplomats involved in the incident at a roadblock on the edge of the capital, Harare, had just completed a tour of hospitals and an alleged torture camp when police demanded they prove they had official permission to visit the sites.

The confrontation was "a message to us, to try to control what we are doing," said U.S. Embassy spokesman Paul Engelstad, who was among about 50 diplomats and journalists on the tour.