Taiwan’s central bank has warned “a few foreign investors” against violating its capital controls as it seeks to contain volatility in its rapidly appreciating currency.

In a statement to the Financial Times, the Central Bank of the Republic of China said it had “strengthened communication with a few foreign investors” and “asked them to self regulate and make necessary improvements” after finding that foreign capital inflows were not being invested in domestic securities. It did not name the investors.

The warning comes as the central bank seeks to rein in the New Taiwan dollar’s sharp rally without being labelled as a currency manipulator by the US. The Taiwan dollar has strengthened more than 10 per cent this year, threatening an economic model built around the country’s enormous trade surplus.