THE United Nations said Thursday it could not disown Zimbabwe's U.N. ambassador, as the country's Prime Minister urged, but it is urging full implementation of a power-sharing deal between the minister and President Robert Mugabe.

Prime Minister Morgan Tsvangirai sent letters Tuesday asking the U.N., the European Union and four nations not to recognise six ambassadors that Mugabe appointed without consulting him.

Tsvangirai argues the February 2009 power-sharing agreement signed with Mugabe requires the coalition partners to agree on all senior appointments.

U.N. deputy spokesman Farhan Haq said Zimbabwe's Ambassador Chitsaka Chipaziwa was properly accredited on June 28 and the U.N. "will be bound by the letter of his accreditation until advised otherwise by the Ministry of Foreign Affairs."

But he said Secretary-General Ban Ki-moon "believes that the Prime Minister's letter highlights a source of concern regarding the political transition in Zimbabwe."

The secretary-general urged the parties to "to respect the commitments they made ... and ensure that the agreement is implemented … entirely in the interest of stability in Zimbabwe and the welfare of its people," Haq said.

Ban also encouraged the guarantors of the agreement — the African Union and the Southern African Development Community, a regional group — to "help build trust between the Zimbabwean parties," he said.

Haq said "the United Nations has expressed its readiness to support that process, if requested to do so."

Tsvangirai asked the U.N., EU, Italy, Sweden, Switzerland and South Africa to reject the diplomatic credentials of incoming ambassadors saying the postings were made "illegally and unconstitutionally" and should not be recognised.

In another blow, Tsvangirai's party said Mugabe unilaterally reappointed 10 provincial governors and five new judges.

Despite the criticism of Mugabe, Tsvangirai insisted he won't be pulling out of the coalition government.