Asia's forex intervention may be a losing game

Asian central banks have sold U.S. dollars in recent sessions in an attempt to rescue their battered currencies, but their efforts may prove futile against a resurgent greenback that has caught fire after a seven-year decline.

Many Asian currencies, which enjoyed a good run last year, have been hammered since late July, as the dollar soared amid concerns over capital outflows and slower economic growth in the region.Authorities in Thailand, Malaysia, Indonesia, India and the Philippines were spotted selling dollars in the foreign exchange market this week. South Korea intervened on Friday for a third day to defend the struggling won,

But so far, these attempts have been unsuccessful as the dollar's surge is just too strong to overcome, analysts say.

"At this point, they're (central banks) not trying to reverse it," said Win Thin, senior currency strategist at Brown Brothers Harriman in New York. "There is no way they can do it. The dollar is gaining across the board, But they are trying to sort of slow the move," Thin said. "They just want to make sure the market remains orderly."

Plunging oil prices, worsening global prospects, and expectations of eventual U.S. interest rate increases have underpinned a month-long recovery in the dollar.