US Federal Reserve chair Janet Yellen has told the US Congress that possible changes President Donald Trump could make to fiscal policy is contributing to economic "uncertainty" in the country.

Speaking on Tuesday as part of her semi-annual testimony to lawmakers, Ms Yellen also seemed to suggest that a rise in interest rates could come sooner rather than later.

Discussing the fact that labour market statistics for the US continue to be strong and inflation is edging up towards her organisation's 2% target, Ms Yellen said it "probably will be appropriate to raise interest rates further" in upcoming meetings of the Fed.

Analysts saw her comments that "every meeting is live" as an indication that rates could go up at any time - possibly next month.

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The Federal Reserve raised interest rates by 0.25% in December, only the second time it has done so since they were cut to near-zero during the 2008 financial crisis.


Ms Yellen has indicated in the past that she expects to raise them again a "few" times before 2019.

But at other points in her testimony Ms Yellen noted that a lack of clarity surrounding the new president's plans for fiscal reform meant that the economic situation in the US remains uncertain.

Stressing the importance of "improving the pace of longer-run economic growth and raising American living standards with policies aimed at improving productivity", Ms Yellen nonetheless refused to weigh in on particular tax or spending proposals.

But she cautioned that any decisions should be made with the aim of maintaining the US budget's "sustainable trajectory".

She also commented that any curbs on immigration - one of the key policy aims of the Trump administration - risks putting economic progress in danger.

Amid an aging US population, "immigration has been an important source of labour force growth", Ms Yellen said, noting that "slowing the pace of immigration probably would slow the growth rate of the economy".