* Yosano says Tokyo believes dollar will remain key currency
* Yosano: strong dollar benefits U.S., world economies
By Leika Kihara
TOKYO, June 25 (Reuters) - Japanese Finance Minister Kaoru Yosano reiterated his support for Washington's strong-dollar policy on Thursday, saying it benefits not only the United States but countries around the world.
The dollar has been buffeted by debate about its status as the world's reserve currency as countries which use Treasuries to park dollars in their foreign exchange reserves, such as China, have fretted about the ballooning supply of U.S. government debt.
Yosano repeated there was no change in Tokyo's policy of regarding the dollar as the world's key currency and the dominant currency for trade settlement.
"The U.S. policy is clearly to support a strong dollar. Our trust in this policy has not wavered at all," he told a financial committee of parliament's upper house.
Yosano made the remarks when asked by a lawmaker for his view on doubts expressed by some big emerging countries about the dollar's dominance.
The dollar index, a measure of the greenback's performance against six other major currencies, rose to its highest in nearly three years earlier this year as financial markets weathered the global economic crisis.
The index has since fallen 10 percent as investors have begun to move out of safe-haven dollar assets and the Federal Reserve has been buying U.S. government debt.
Russia suggested earlier this month the need for a global reserve currency other than the greenback, fuelling speculation that a meeting of big emerging nations could make a joint assault on the U.S. dollar's dominance.
But the summit of the so-called BRIC nations of Brazil, Russia, India and China last week steered clear of the debate, indicating little unity on any potential challenge to the dollar. (Editing by Michael Watson)