GENEVA (Reuters) - Switzerland has won the backing of G20 chairman Britain for its efforts to stay off an international blacklist of uncooperative tax havens, the finance ministry said on Saturday.

Finance Minister Hans-Rudolf Merz met British Prime Minister Gordon Brown in London on Saturday, the day after Switzerland offered to relax its strict banking secrecy in some tax evasion cases, the ministry said in a statement.

Merz said on Friday when he announced the relaxation that it was prompted by fears that the summit of heads of G20 rich and emerging countries hosted by Britain on April 2 could blacklist Switzerland with other tax havens, damaging not only its financial sector but ultimately its export industries. The move, together with Luxembourg and Austria, and following similar concessions by other financial centres, was intended to head off a crackdown on tax havens by the United States, European Union and other countries as they scramble for funds to battle the economic crisis.

"Prime Minister Brown said that his government would support Switzerland's stance that the G20 should not place Switzerland on a list of uncooperative states," the ministry said.

"He also promised that his government would support direct Swiss involvement in G20 activities at least on a technical level."

A spokesman for the British prime minister confirmed Brown had met Merz on Saturday. He gave no details but pointed out that Britain has welcomed Swiss moves to relax bank secrecy rules.