The Federal Reserve has said it will keep buying at least $120bn of debt per month until “substantial further progress has been made” in the recovery, strengthening its support for the US economy amid a surging coronavirus outbreak.

The guidance from the Federal Open Market Committee came at the end of a two-day meeting during which Fed officials upgraded their economic projections but maintained predictions that they would keep interest rates close to zero until at least the end of 2023.

The language on debt purchases mirrors the Fed’s pledge to keep interest rates close to zero until the economy reaches full employment and inflation is on track to exceed its 2 per cent target for some time.

But it fell short of calls for more forceful monetary stimulus to tackle the fading recovery by lengthening the average maturity of its bond purchases or increasing the aggregate size.

“The Federal Reserve will continue to increase its holdings of Treasury securities by at least $80bn per month and of agency mortgage-backed securities by at least $40bn per month until substantial further progress has been made toward the committee’s maximum employment and price stability goals,” the FOMC said.

“These asset purchases help foster smooth market functioning and accommodative financial conditions, thereby supporting the flow of credit to households and businesses,” it added.

The guidance sets a longer horizon for the Fed’s bond purchases; the previous statement said they would only continue over the “coming months”. The rest of the FOMC statement was virtually unchanged, with policymakers describing the economy as recovering from the hit caused by the pandemic but still operating well below capacity.

During the press conference following the FOMC’s last meeting of the year, Jay Powell, the Fed chairman, called the new guidance on asset purchases a “powerful message” about the central bank’s determination to keep supporting the recovery.

“What we’ve done is we’ve laid out a path whereby we’re going to keep monetary policy highly accommodative for a long time . . . until we reach very close to our goals, which is not really the way it’s been done in the past,” he said.

The Fed chairman nonetheless stressed that fiscal policy would be the most effective way to navigate the economy’s rough patch in the coming months. “It looks like a time when what is really needed is fiscal policy and that’s why it is very positive thing that we’re getting that,” he said, as Congress moved closer to a $900bn stimulus package.

According to the projections of the median Fed policymaker, the US economy is expected to shrink at a rate of 2.4 per cent in 2020, followed by a rebound of 4.2 per cent next year, both slightly better figures than the central bank’s forecasts in September.

While recent economic data has shown a slowdown in the labour market recovery and weakness in retail sales, the medium-term picture has improved as a result of a faster-than-expected rollout of Covid-19 vaccinations.

US central bankers’ expectations for the timing of interest rate rises were largely unchanged, with only one out of 17 expecting higher rates in 2022, and five expecting a rise in 2023.

Long-dated US Treasuries initially sold off after the statement, sending the yield on the benchmark 10-year note higher by 0.03 percentage points to 0.94 per cent before retreating. Two-year Treasuries budged little, the yield steady at 0.12 per cent.

The S&P 500 slipped before climbing again to close 0.2 per cent higher.

Peter Tchir, chief macro strategist at Academy Securities, said the brief sell off reflected some disappointment among investors about the Fed’s decision to hold off on adjusting its bond-buying programme. “There was some hope they would be a little bit more aggressive, he said.