US President Donald Trump wears a mask as he tours a lab where they are making components for a potential vaccine at the Bioprocess Innovation Center at Fujifilm Diosynth Biotechnologies in Morrisville, North Carolina. Photo: AFP

US President Donald Trump on Saturday signed a series of executive orders to extend certain COVID-19 economic relief after negotiations between Republican and Democratic lawmakers fell apart.

One of the president's four orders will extend extra unemployment benefits through the end of the year at a reduced level of 400 US dollars per week, instead of the 600 dollars approved by Congress in late March, which expired at the end of July.

The other orders will reinstate the federal moratorium on evictions, which also expired at the end of July, defer student loan payments through 2020, and defer certain payroll tax obligations.

Trump's orders will likely face a legal challenge, as Congress has the constitutional authority to determine federal funding, according to US media.

Earlier in the week, Democrats offered to cut their 3.4-trillion-dollar relief proposal by 1 trillion dollars if Republicans would agree to increase their roughly 1-trillion-dollar package by the same amount, but were rebuffed.

Trump said Friday that he would sign executive orders to provide certain relief if no deal is reached with Democrats.