FACTBOX: Developments in Zimbabwe

(Reuters) - Following are latest developments in Zimbabwe:

** Denotes new or updated item:

** Former South African President Nelson Mandela expresses concern over the crisis and criticizes Zimbabwe's leadership.

** U.S. President George W. Bush calls run-off election a "sham".

* Britain's foreign ministry advises against travel to Zimbabwe.

* Three hundred Zimbabweans seek refuge at the South African embassy in Harare, a South African government spokesman said.

* Britain strips President Robert Mugabe of honorary knighthood.

* Leaders of a security troika of the Southern African Development Community (SADC) called for a postponement of Zimbabwe's run-off election, saying conditions were not conducive to a fair poll.

* A top South African negotiator is in Zimbabwe to broker talks that will consider all options, including postponement of the election.

* Zimbabwe's electoral commission said that the opposition's withdrawal from June 27 run-off has no legal effect and the vote will go ahead.

* Zimbabwe election monitors said they could not effectively observe the presidential vote because of threats to their safety.

* Opposition leader Morgan Tsvangirai said the African Union, backed by the United Nations, should lead a transitional process in Zimbabwe following disputed elections and violence.

* Tsvangirai said his opposition MDC would not enter negotiations with President Robert Mugabe's government if the run-off election goes ahead.

* Tsvangirai spoke from his home, which he visited for a short time before returning to the Dutch embassy, where he has taken refuge.

* The England and Wales Cricket Board (ECB) cancelled Zimbabwe's tour of England next year under instructions from the British government.

* Britain said it is preparing intensified sanctions, financial and travel sanctions, against named members of the Mugabe regime.