Zimbabwe's Prime Minister Morgan Tsvangirai has expressed concern about rising political violence in the country.

During a press conference in Harare Wednesday, Mr. Tsvangirai specifically blamed the police for the situation, saying they are the source of instability, ignoring the law and undermining peace.

He said the violence is designed and executed by people who want to reverse progress made since his Movement for Democratic Change party went into power-sharing government with President Robert Mugabe's ZANU-PF party almost three years ago.

The prime minister said he met with Mr. Mugabe Tuesday after armed police raided MDC headquarters in Harare and fired tear gas. He said they both agreed that political violence in Zimbabwe must stop.

When asked about the cost of the president's frequent trips to Singapore for medical treatment, Mr. Tsvangirai defended the expense, saying it is the responsibility of the state to look after its leaders.

Zimbabwe's Finance Minister Tendai Biti has complained that foreign travel by senior political leaders, including Mr. Mugabe and Mr. Tsvangirai, is very costly to the country's economy.

The prime minister said he is not guilty of overspending on foreign travel, and asked that Biti break down the expenditure for each individual.