The foreign secretary has formally welcomed the suspension of Zimbabwe from the Commonwealth.

The decision was taken earlier this week by a "troika" made up of the heads of government of South Africa, Nigeria and Australia.

They ruled that conduct by Robert Mugabe and his ruling Zanu PF party warranted a one year suspension from the councils of the Commonwealth.

Jack Straw gave the government's "full support" to the Troika's conclusions.

"The commonwealth depends above all on its moral principles...that is why the decision was so important," he told MPs.

"It is that moral authority that gives this decision its force."

Straw said that fact that leaders of two key African nations had backed the decision "underlined Africa's commitment to the universal and indivisible principles of democracy and human rights".

Describing what has happened in Zimbabwe as a "tragedy", he said there was still a "very strong" justification for lawful land reform and Britain was still ready to support such measures.

"Return to the rule of law...is the only way back for Zimbabwe," said Straw.

He said the UK would continue humanitarian assistance but admitted that "in the short term, the prospects for Zimbabwe look bleak".

Shadow foreign secretary Michael Ancram also welcomed the troika's decision, saying Australian premier John Howard "has succeeded where many thought he would fail".

And he called for tougher action against president Mugabe.

Referring to the decision to charge opposition leader Morgan Tsvangirai with treason, he said the move "should be seen as a hostile action against all those who believe in democracy".

He called on the government to build an international alliance to halt any inappropriate charges.

And he called for Zimbabwe to be excluded from the Commonwealth Games

"The United Kingdom has to make it clear that Zimbabwe is not welcome at the Games," he urged.

Condemning the government's record, he concluded that "history will record that this government got it wrong, and it is time they admitted it".

"The time has come for the government to stop talking and start doing," Ancram said.

Responding to the call for action on the Commonwealth Games, Straw said it was a matter for the Commonwealth Games Federation.

Young people involved in sport were not those responsible for breaching human rights in Zimbabwe, he argued.

Liberal Democrat foreign affairs spokesman Menzies Campbell also welcomed the suspension, but said it was "overshadowed by a profound anxiety for the people of Zimbabwe".