Gold prices edged lower on Thursday, following a steep sell-off in the previous session, as a breakthrough in long-running US fiscal stimulus negotiations remained elusive.

Spot gold slipped 0.2% to $1,835.40 per ounce by 0707 GMT, after falling as much as 2.5% on Wednesday. US gold futures were steady at $1,839.20.

"Gold has struggled as markets are disappointed with the inability of US lawmakers to agree on a fiscal deal they were anticipating," said Lachlan Shaw, National Australia Bank's head of commodity research.

Lawmakers in the United States extended federal government funding by a week to give them more time to agree on a coronavirus relief package. But US Senate Majority Leader Mitch McConnell said they were still looking for a way forward.

"We could be seeing a regime change in gold markets as its correlation to real yields has weakened, due to investors continuing to move into riskier assets, creating a challenging outlook for safe-havens like gold," Shaw said.

Investors now await the European Central Bank's monetary policy decision, due at 1245 GMT, where it is expected to unveil fresh stimulus measures, and US weekly jobless claims data, due at 1330 GMT.

"Any immediate gains in spot gold would have to battle the ongoing tide of outflows from gold exchange-traded funds," said FXTM market analyst Han Tan.

"Ultimately, gold is due for another boost, either from the next injection of US fiscal stimulus, or stronger signals out of the Federal Reserve with regards to boosting inflationary pressures."

Meanwhile, a British regulator cautioned against the use of Pfizer's COVID-19 vaccine for those with allergies, after two people suffered adverse reactions, cooling optimism over a smooth vaccine rollout.