TOKYO  The Japanese government is gearing up to intervene in global currency markets to curb a strengthening yen, Prime Minister Naoto Kan said Friday, signaling an effort to limit further damage to Japan’s export-led economy.

Any intervention is expected to do little to stem the yen’s rise in the long term, however, especially without cooperation from the United States or Europe, which are happy to see their exporters gain a competitive edge against the Japanese.

Increased purchases of yen-dominated bonds by China, which is seeking to diversify its foreign reserves away from the dollar, could also add to the upward pressure on the yen. And as long as the yen is still seen as a relative safe haven by investors, the buying is unlikely to stop, analysts say.

Mr. Kan repeated a common refrain from Japanese officials in recent weeks: that Tokyo was ready to act as needed to curb the yen’s advance. This time, though, he spoke in more detail than before about a possible intervention, saying Japanese officials were in talks with their counterparts overseas to lay the groundwork for such a maneuver.