The greenback hit session lows versus the euro and yen after Powell's comments, which reinforced expectations the Fed will cut interest rates for the first time in a decade at its next monetary policy meeting later this month.

In prepared remarks to a congressional committee, Powell said the Fed stands ready to "act as appropriate" to sustain a decade-long expansion.

He also contrasted the Fed's "baseline outlook" of continued US growth against a considerable set of risks - including persistently weak inflation, slower growth in other major economies, and a downturn in business investment driven by uncertainty over just how long the Trump administration's trade war with China and other countries will last and how intense it will become.

In early morning trading, the dollar fell 0.2pc versus the yen to 108.66, while the euro rose 0.3pc against the dollar to $1.1244.