"The change we are making is the first major revision in the surveillance framework in some 30 years, and it is the first ever comprehensive policy statement on surveillance" of exchange-rate policies, the IMF managing director, Rodrigo Rato, said in Montreal, according to the published text.

The new policy was adopted Friday by the 24-member executive board in Washington.

At the heart of the new legal framework for surveillance is the guiding principle of external stability, the 185-member IMF said.

In addition to updating and broadening guidelines to reflect best practices that were not envisioned in the 1977 Decision on Surveillance over Exchange Rate Policies, the new policy focuses on the external effects of monetary policy.

It established four guiding principles for members' exchange-rate policies, including a new one: "A member shall avoid manipulating exchange rates or the international monetary system in order to prevent effective balance of payments adjustment or to gain an unfair competitive advantage over other members."

The Fund also toughened its definition of factors that could lead to a review of foreign-exchange policies and the opening of bilateral discussions on the subject with a member country.