South Korea's foreign exchange authorities reportedly carried out a rare dollar-selling intervention on Thursday, according to a market source cited Friday. The move pushed the won to its strongest level in about nine months, highlighting an unusual step by Seoul in the currency market.

The reported action came at the same time as Japan was buying yen and selling dollars, linking two of Asia's biggest economies in efforts that affected regional currency trading. Such intervention is closely watched because it can quickly shift exchange rates and influence broader market sentiment.

A dollar-selling operation by South Korea would typically support the won by increasing demand for the local currency. The fact that the won climbed to a nine-month high suggests the market reacted strongly to the reported move and to the wider signal sent by coordinated pressure on the dollar.

While the trimmed report does not detail the full policy backdrop, the intervention stands out because direct action by Seoul in the foreign exchange market is considered uncommon. Investors will now be watching for any official confirmation and for signs of whether the won's strength can be sustained in coming sessions.