The Australian dollar has surged higher overnight, easily clearing the US77¢ mark to its highest since the US election, and positive January jobs data could solidify its advance, according to NAB economists.

The currency rallied more than 1 per cent from an overnight low of US76.37¢ to jump over the US 77 cent mark. It was further boosted by Thursday's employment figures, reaching a high of 77.32 US cents just after 11:30 AEDT.

The Aussie, which has risen 6.8 per cent so far in 2017, managed to press through a key technical trading level, said NAB economist Rodrigo Catril, adding it "now has more freedom" to move still higher.

In Washington, Federal Reserve chair Janet Yellen testified before US lawmakers for a second day, reiterating her expectation that the central bank will be looking at lifting interest rates in the months ahead as the world's largest economy expands bolstering both the labour market and inflation.