The Conservative Party has criticised Foreign Office ministers over their announcement of a replacement for the current British ambassador to Romania.

The Foreign Office announced on Wednesday that the ambassador currently posted to Bucharest, Richard Ralph, will be replaced in November by Quinton Quayle.

The news prompted shadow Cabinet Office minister Tim Collins to condemn the government for being more concerned with "big ticket Labour donors than the interests of the British people".

Ralph, the outgoing ambassador, became embroiled in the row over government support for Indian steel tycoon Lakshmi Mittal after it emerged he had made a £125,000 donation to the Labour Party.

At the height of the row it was revealed that Ralph asked the prime minister to give his backing to Mittal's attempt to take over Romania's biggest steel manufacturer.

Tony Blair said he had given his support because Mittal's company was "British", even though it later emerged that it employed fewer than 100 peoplein Britain and was registered in the Dutch Antilles.

The Foreign Office said the move had "absolutely nothing" to do with the Mittal row. "Richard Ralph is moving on to another job. There is no question of him being recalled," said a spokesman.

But Tim Collins said there were questions to be answered over the choice of Ralph's successor. He questioned whether Quayle had also previously been involved in backing Mittal.

"This is a quite extraordinary development. For New Labour to parachute into Bucharest a man who has already, it seems, aided Mr Mittal indicates that under this government it is more important for British ambassadors to represent big ticket Labour donors than the interests of the British people," he said.

"We will be pressing for clear answers from the foreign secretary and the prime minister as soon as parliament returns."