Asian currencies struggle

Most Asian currencies weakened on Wednesday on worries that the sealing of a first-phase trade deal between the United States and China could be delayed.

The optimism around a partial resolution to the festering trade dispute faded a bit after a US administration official told Reuters that an interim agreement might not be completed in time for signing in Chile next month as expected.

The trade dispute and the chance for at least a partial resolution continues to be a key factor in currency markets.

Asian financial markets also tread water as the focus shifted to the US Federal Reserve decision later on Wednesday. The market has priced in 25 basis points US rate cut.

"Fed is likely to maintain some degree of optionality with regard to future policy guidance, without over-committing," Maybank analysts said in a note.

"It (Fed) could possibly go a step further to signal that the mid-cycle adjustment has ended, akin to hawkish cut."

Investors will also await US third-quarter GDP figures, due on Wednesday ahead of the Fed decision. Any weakness in the data could increase worries on global growth.

The South Korean won, which gained about 1% on Monday and Tuesday combined, slid as much as 0.6%, its biggest percentage intraday drop in nearly three weeks.

The Indian rupee, which had a solid advance in the previous session, slipped as much as 0.3% on the day.

The Indonesian rupiah, the Malaysian ringgit and the Thai baht weakened slightly, while the Singapore dollar and the Philippine peso barely moved.

The Chinese yuan inched up marginally after trading flat in the first two sessions of the week as investors mark time ahead of the Fed decision.

The Taiwanese dollar appreciated 0.13%. A Reuters poll showed economists expect the island's third-quarter GDP growth rate - due on Thursday - to be 2.5%, barely changed from April-June's pace.