Mr Maduro who came to power in 2013 after Chávez died.

image copyright Getty/EPA

The US has criticised Mr Maduro's increased use of the country's courts and security forces to suppress political opposition.

They declared his re-election last year as "illegitimate" and imposed a raft of economic measures against Venezuela.

image copyright Getty Images image caption The US houses about 100,000 Venezuelans - many who oppose Mr Maduro

In turn, US sanctions have been used as a scapegoat by Mr Maduro to shift blame for the country's economic woes.

Amid a deepening economic crisis, Venezuela has struggled to utilise its supply of the world's largest proven oil reserves.

US purchases of that oil have declined sharply - but companies still import about 500,000 barrels from the country daily.

This amounts to about 41% of Venezuela's totaloil exports, the Associated Press reports.

Crucially, unlike other countries that Venezuela is indebted to, American firms pay for that oil in cash.

Fresh Trump administration sanctions aim to frustrate that source of income by targeting PDVSA, the Venezuelan state oil company. Some refineries have already said they will source oil elsewhere.

One US company, Citgo, is a subsidiary of PDSVA. Under new sanctions it is only allowed to operate if its earnings are deposited into an account blocked from President Maduro.

President Trump has refused to take any option off the table in response to the country's crisis, and his administration had pledged to try and divert oil earnings to Mr Guaidó instead.

European Union countries

Austria, Britain, Croatia, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Latvia, Lithuania, Luxembourg, the Netherlands, Portugal,