Tony Blair is set to renew his condemnation of Zimbabwe's leaders at the Commonwealth summit.

The prime minister and foreign secretary Jack Straw are set to criticise the government of President Mugabe during the summit in Nigeria which gets underway on Friday.

The Zimbabwean president has not been invited to the meeting following a rigged election and a growing number of human rights abuses.

Number 10 blamed the deteriorating situation in Zimbabwe purely on the Mugabe leadership.

"There is a growing consensus at the top level that Zimbabwe has failed to meet the benchmarks that the Commonwealth had laid down," said the official spokesman.

Britain will join the calls of other heads of state for Mugabe to stand down.

"It will be good for the people of Zimbabwe who are facing a crisis which is not a result of any outside interference. It is a government-made crisis," said Number 10.

Other issues to be discussed will be global terrorism, HIV and polio.

Britain is also expected to use the summit to call for Pakistan to be readmitted to the Commonwealth.

Pakistan was suspended after General Musharraf's 1999 military coup but the country has played a key role in ousting the Taliban from Afghanistan.

Britain and Australia are calling for Pakistan to be allowed back but African countries have rejected the move.

The Queen, who is head of the Commonwealth, has already arrived in the country which is using the summit to highlight its return to democratic rule.Nigeria's leader, President Olusegun Obasanjo, is a former political prisoner who is credited with bringing the country back from the brink of chaos.

But there are still human rights issues on the agenda, particularly over the use of public stonings in some parts of the country.

The rise of Islamic terrorist groups in the region mean the trip is subject to tight security.