Gold prices firmed above the key $1,800 mark on Tuesday, buoyed by a retreat in the dollar and US Treasury yields, as investors awaited cues on expected policy tightening from Federal Reserve Chair Jerome Powell.

Spot gold was last up 0.1% at $1,803.20 per ounce by 09:47 ET. US gold futures rose 0.3% to $1,804.00.

Higher crude oil prices, a weaker dollar and a slight pullback in US Treasury yields are supporting gold prices, said Jim Wyckoff, a senior analyst at Kitco Metals.

However, the gold market is going to react negatively to any surprising, hawkish comments from Powell because bulls will look at the US dollar and Treasury bond yields that will probably rise, Wyckoff added.

Although gold is often seen as a hedge against oil-led inflation, higher interest rates will curb the appeal for the non-yielding bullion by increasing its opportunity cost.

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US stock indexes fell on Tuesday. Powell is set to appear before the Senate Banking Committee at 10 a.m ET for consideration for a second four-year term as head of the Fed.

Powell had pledged "to prevent higher inflation from becoming entrenched" in comments prepared for delivery at his hearing.

The US core CPI data on Wednesday, which is expected to have risen by an annual 5.4% in December from 4.9% in the prior month, is also on investors' radar.

However, despite higher odds of an earlier start to the Fed's balance sheet runoff, "the yellow metal is within touching distance of the $1,812/oz region which could see a large net long position targeted once again," TD Securities said in a note.

Silver edged up 0.1% to $22.47 an ounce, platinum was up 0.1% at $940.54 and palladium fell 0.4% to $1,905.68.