A bomb exploded at a busy Zimbabwean rail and road hub linking capital Harare with second main city Bulawayo, causing minor damages to property but no injuries, police said on Friday.

"There was an attempt to bomb the Hunyani rail and road bridges along the Harare-Bulawayo routes last night," police spokesperson Wayne Bvudzijena said in a statement.

"Both bridges (where the bomb exploded) suffered minimum damage and remained intact and useable."

No arrests have been made yet, he said.

The blast comes three weeks after a bomb exploded at Harare's main police station, shattering windows and causing minor damages but no injuries.

State-owned Herald newspaper reported that junior police officers had been arrested over the explosion.

Last year, Zimbabwe was hit by a spate of fire bombings targeting police stations, with police blaming the main opposition Movement for Democratic Change (MDC) party.

The MDC however denies the accusations.

Zimbabwe has been plagued by political turmoil and violence, heightened after the country's March election results, in which the opposition won the legislative vote and MDC leader Morgan Tsvangirai won the first round of presidential voting.

In June, veteran president Robert Mugabe was re-elected in a one-man run-off boycotted by Tsvangirai.

Power-sharing negotiations between the ruling party and the MDC, aimed at resolving the country's political impasse, were suspended a week ago.

MPs elected in the March poll will be sworn in Monday, while President Robert Mugabe is expected to convene the new parliament the following day, in a move Tsvangirai opposes.