Asian currencies turned early gains against the dollar into modest losses late on Thursday, led by the Indonesian rupiah after the country's central bank said it would tighten foreign exchange trading rules. The rupiah was down about a fifth of a percent against the dollar at 9,610, nearing Monday's seven-week low of 9,640.
The Taiwan dollar was steady at 31.41 per US dollar, holding above Wednesday's seven-week low around 31.51 and drawing some support from Taiwan stocks, which closed at their highest level in more than 13 months.
Indonesia's central bank said certain foreign exchange deals would be banned, including buying rupiah-denominated securities issued by non-residents. The measures are designed to stabilise the rupiah, one of Asia's worst-performing currencies this year.
"The market's first reaction was to buy dollar/rupiah. The longer-term implication is that liquidity will become more restricted and may actually lead to greater volatility," J.P. Morgan currency strategist Claudio Piron wrote in a note following the move by the central bank.
"The near-term risk is that dollar/rupiah spot could be squeezed higher even further," he said, adding that offshore investors have been net sellers of dollar/rupiah forwards.
The foreign exchange move in Indonesia comes after the authorities in Thailand tightened some controls this week. In contrast, South Korea said this week it would ease currency regulations in an effort to curb the strength of the won.
Some analysts said the new rules could benefit the rupiah in the short term - the currency has shed more than three percent against the dollar so far this year.
The South Korean won ceded early gains to trade almost 0.2 percent lower at 1,014.10 per dollar. Strong demand for dollars from importers undermined the won in late trade, dealers said.
Asian currencies opened slightly higher after the dollar took a hit from data overnight showing capital inflows into the United States in April failed to cover the trade deficit for the second month in a row.
But the dollar had recovered ground against major currencies by late trade, thanks in part to worries about the future of the European Union that weighed on the euro.
General strength in equity markets was supporting regional currencies, dealers and analysts said. Foreigners have been net buyers of Taiwan stocks every day this month except for one.
The Singapore dollar was trading at 1.6751 per dollar, holding above Monday's eight-month low, while the Philippines peso was slightly weaker at 55.34 per dollar and close to this week's four-month lows at around 55.45.
The Thai baht traded at 40.95 per US dollar and within striking distance of Wednesday's seven-month low of 40.99.
The 41 per dollar level is proving a significant support level for the baht and technical analysts say the dollar has struggled to break through this chart barrier in the past.