US President Donald Trump has signed executive orders extending economic help to Americans hit by the coronavirus crisis after his Republican party and opposition Democrats failed to agree on a new stimulus package.

It comes as the United States set a record for Covid-19 cases today, with more than five million people now infected, according to a Reuters tally.

With one out of every 66 residents infected with coronavirus, the US has recorded more than 160,000 deaths, nearly a quarter of the world's total.

"We've had it and we're going to save American jobs and provide relief to the American workers," Mr Trump said at a press conference in his golf club in Bedminster, New Jersey.

With double digit unemployment, massive disruption to businesses from social distancing rules, and stubbornly high rates of coronavirus infection, many Americans have been relying on relief measures approved earlier by Congress.

However, most of these expired in July. Mr Trump said his decision to circumvent Congress with executive orders would mean relief money getting "rapidly distributed".

One order aims to get $400 a week added to unemployment benefits, while two others offer some protection from evictions and relief for student loans.

A fourth measure - opposed by many Republicans as well as Democrats - orders a freeze in payroll taxes.

President Trump, speaking in the ballroom of his Bedminster, New Jersey golf club with an audience of club members cheering him and laughing at his colourful insults against opponents, said he was also working on new tax cut ideas.

However, his executive orders are likely to face court challenges, since they short-circuit Congress, which has constitutional power over most spending decisions.

Democrats, Republicans and White House negotiators had worked all last week without coming close to a deal on a congressional relief bill.

Democrats had pushed for a massive new $3 trillion stimulus package aimed at propping up the economy, repairing the tattered postal system in time for the presidential election, and giving the unemployed an extra $600 a week.