Washington DC: US President Donald Trump has rejected a nearly $900bn emergency spending legislation to tackle the COVID-19 pandemic that took months to negotiate, telling Congress to amend the bill and increase the amount of relief to Americans, among other demands.

Trump assailed the bipartisan $900 billion package in a video he tweeted out Tuesday night and suggested he may not sign the legislation. He called on lawmakers to increase direct payments for most Americans from $600 to $2,000 for individuals and $4,000 for couples.

While he did not explicitly say he would not sign the bill, which passed overwhelmingly Monday in both houses of Congress, Trump made clear he would not accept the legislation.

"It really is a disgrace," he said in a video message posted to Twitter.

"I am asking Congress to amend this bill and increase the ridiculously low $600 to $2,000, or $4,000 for a couple," he said, referring to relief checks meant to go out to most Americans.

"I'm also asking Congress to immediately get rid of the wasteful and unnecessary items from this legislation, and just send me a suitable bill."

US government operations are being funded on a temporary basis through December 28 waiting for the $1.4 trillion in federal spending for fiscal 2021 that is also part of the bill.

Failure to either pass another stopgap bill or override a possible Trump veto of the legislation could result in a partial government shutdown.

The outgoing Republican President's threat, with less than a month left in office, throws into turmoil a bipartisan effort in Congress to provide help for people whose lives have been upended by the pandemic.

(With inputs from agency)