The Federal Reserve intervened in the currency market Friday, buying dollars and selling yen as part of a coordinated effort by Group of Seven nations to weaken Japan’s currency.

It was the first coordinated currency intervention since 2000. The intervention began in Tokyo with the Bank of Japan intervening. The Bank of England, Bundesbank, Banque de France and Bank of Italy all intervened during European trading, and the Bank of Canada also intervened.

The initial intervention from the Fed came right at 8 a.m. EDT, the start of the New York trading day. Three U.S. banks familiar with the intervention told Dow Jones Newswires the Fed’s trades early in the New York day totaled about $50 million.

The initial intervention by the Fed was symbolic to show the central bank stood with the Bank of Japan in the coordinated effort, said Michael Woolfolk, senior currency strategist at Bank of New York Mellon in New York. But he added that it was also a “warning shot across the bow” of speculators trying to fight the intervention.

The dollar spiked to Y81.76 in the first minute of trading in New York, but has since pulled back. It was most recently trading at about Y81.15.

Based on the price action, the Fed and Bank of Canada could be intervening in a more sustained manner, as opposed to a “one-shot deal,” said Brian Kim, currency strategist at UBS in Stamford, Conn.

“It could be maybe they’re going to spread it out,” Kim said of measures to curb yen strength. “Or maybe that was it.”

When all is said and done, the dollar may be propped to Y82, Kim said, which could be a psychologically significant number and would bring the dollar back to pre-earthquake levels.

Nomura Securities said intervention could continue into next week as the Bank of Japan makes further attempts to weaken its currency. Nomura said the ideal dollar target level is between Y82.70 and Y83.00.

The yen had been strengthening as traders bet Japanese insurers and corporations would need to repatriate yen to help pay for rebuilding the country after last week’s major earthquake and tsunami.

The dollar fell to a record low of Y76.25 early in Thursday’s global session, shattering the previous low of Y79.75.

The Fed had $11.922 billion worth of yen-denominated assets, as of the fourth quarter.