Most US central bankers viewed inflation as stable, but some are becoming more vocal about fears the Covid-19 pandemic will push prices higher, according to minutes of last month's Federal Reserve meeting. 

Fed officials also expressed concern the pandemic was constraining the American labour force. 

The policy-setting Federal Open Market Committee (FOMC) took no major action at the March 16-17 meeting.

It kept its benchmark lending rate at zero to help the economy recover from the business disruptions and mass layoffs caused by Covid-19. 

While warning the recovery was incomplete, Fed Chair Jerome Powell acknowledged the rebound has been faster than expected thanks to relief measures approved by Congress, including the $1.9 trillion American Rescue Plan enacted last month. 

However, the massive spending has raised fears inflation will increase as the world's largest economy reopens, which sparked a selloff in bonds and some rocky trading sessions on Wall Street.

The FOMC meeting minutes showed most Fed members saw inflation as under control, with the risks "broadly balanced," but there was a split on the fear prices could spike. 

"Several remarked that supply disruptions and strong demand could push up price inflation more than anticipated," the minutes said.

But "several participants commented that the factors that had contributed to low inflation during the previous expansion could again exert more downward pressure on inflation than expected," the minutes added. 

Meanwhile, despite the strengthening recovery, Fed members warned that "the path ahead remained highly uncertain, with the pandemic continuing to pose considerable risks to the outlook." 

In particular, they raised concerns about the labour force participation rate, a measure of the economy's active workforce, which in February was at 61.4%. 

Though it has recovered from the lowest point of the pandemic, it is near levels not seen since the mid-1970s.

Some committee members worried "labour force participation continued to be held down by workers' health concerns and additional childcare responsibilities associated with virtual schooling," and would not improve until those are addressed. 

In the March employment data released last week, the labour force participation rate posted a miniscule increase to 61.5% compared to 63.4% in January 2020.