The foreign secretary's failure to speak out about the situation in Zimbabwe "shames" Britain, according to Michael Ancram.

In a letter to Jack Straw, the shadow foreign secretary said the government's failure to condemn the policies of president Robert Mugabe stood in marked contrast to its leading role in Kosovo.

Ancram criticised the government's "total silence on the horrors currently facing Zimbabwe".

Comparing the Zanu-PF leader with indicted war criminal and former Serbian president, Slobodan Milosovic, Ancram challenged the government to explain why it had intervened militarily in Kosovo but not in Zimbabwe.

"What is the difference between ethnic cleansing in Kosovo and in Zimbabwe? What is the difference between state murder and torture in Kosovo and in Zimbabwe?" he asked.

"Why was the government so keen to take direct action in Kosovo and is pathetically silent and inactive on Zimbabwe?"

Ancram said Mugabe's attempts to redistribute land from 2900 white farmers compared with the expulsion of an estimated 900,000 ethnic Albanians from Kosovo.

"Mugabe is every bit as evil as Milosovic. His victims are certainly more defenceless," argued Ancram.

He said the government's failure to act raised the question of "whatever happened to the ethical foreign policy?".

And Ancram told Straw that "your silence shames us all".