LONDON - Britain said on Friday it was too early to lift sanctions against Zimbabwe despite the creation of a new unity government in its former colony.

Zimbabwe's Prime Minister Morgan Tsvangirai arrives in Britain later on Friday on the final leg of a tour of Europe and the United States to woo financial support for the unity government he shares with long-ruling President Robert Mugabe.

Writing in the Times, Africa minister Mark Malloch-Brown noted that sanctions were directed against individuals linked to Mugabe's rule and the companies that bankrolled it.

We will not lift the bulk of these measures until we are convinced that Zimbabwe's transition to democracy has reached a point of no return, Malloch-Brown wrote.

He said Tsvangirai's Movement for Democratic Change had taken a leap of faith in entering government with Mugabe, who has ruled since independence from Britain in 1980.

It is beginning to make it work, although there are plenty of pitfalls. Mr Mugabe could easily try to go back on his word and grab absolute power again.

Malloch-Brown said the media in Zimbabwe was not free, political activists were being harassed and farm seizures were continuing. Amnesty International said in a report on Thursday that the government has failed to curb human rights abuses.

Britain pledged 15 million pounds in April in humanitarian assistance for Zimbabwe but has channelled this through the United Nations and non-governmental organisations ran than directly to the government.

The Zimbabwe government says it needs $10 billion (6.1 billion pounds) to rebuild its shattered economy, but most Western donors have been offering limited sums and bypassing the government.