US Secretary of State Marco Rubio has called for Syria's transitional authorities to be supported, warning that the country could be only weeks away from "potential collapse and a full-scale civil war of epic proportions".

Axar.az, citing BBC, reports that Rubio stated this at a hearing of the Senate Foreign Relations Committee.

He defended President Donald Trump's decision last week to lift sanctions on Syria before meeting President Ahmed al-Sharaa, who led the rebel offensive that overthrew Bashar al-Assad in December.

Trump's rationale was that other countries wanted to help Sharaa's administration and send aid, but were afraid of the sanctions, Rubio explained.

There was no immediate comment from Syrian officials.