TOKYO, Sept 20 Reuters The dollar remained firm against a basket of peers on Wednesday ahead of a muchanticipated rate decision by the Federal Reserve later in the day, while the yen continued to hang close to a 10month low.

The U.S. dollar index , which measures the greenback against a basket of rivals, stayed mostly flat at 105.17 as traders awaited the Fed39;s rate decision.

Attention stayed fixed on the yen as U.S. and Japanese authorities heaped on fresh comments about the possibility of intervention.

Markets expect the Fed will almost certainly keep rates on hold at 5.25 to 5.50, putting the focus on the central bank39;s forward guidance.

Futures markets are pricing in a 30 likelihood of a quarterpoint increase in November or 40 chance it will be in December, according to CME FedWatch tool.

We expect the FOMC to retain its forecast of one extra 25 hike by yearend, though it will not follow through with it in our view, said Carol Kong, economist and currency strategist at the Commonwealth Bank of Australia.

Dollaryen could see some upside pressure after a hawkish FOMC meeting, she added.

The yen last sat around 147.83 versus the greenback, off Tuesday39;s low of 147.92 though hovering near the 10month trough against the dollar ahead of the FOMC announcement.

Japan39;s top financial diplomat, Masato Kanda, reiterated warnings on Wednesday, saying Japanese authorities are always in close communication on currencies with U.S. and overseas policymakers while…