Singapore: Venezuela’s state oil company and its customers will be blocked from using the US financial system by late April, as the Trump administration ratchets up the pressure on President Nicolas Maduro to step aside and allow an opposition leader to take his place.

The US already announced it would prohibit imports of Venezuelan crude and bar companies from selling cargoes of light oil to the Latin American country, which are needed to keep its pipelines flowing. The latest measures posted on the Treasury’s website suggest the sanctions could have an even wider impact on the petroleum exports that constitute the nation’s economic lifeline.

Any transactions with Petroleos de Venezuela SA, or any entity in which it has a controlling stake, involving US persons or passing through the country’s financial system must be wound down by April 28, the Treasury said. Americans who work for non-U. S. companies must stop doing any business with PDVSA by March 29.

The US government’s decision to impose sweeping sanctions on PDVSA already looked like it would become a de facto oil embargo on the country. The administration of President Donald Trump has made clear it believes Maduro’s re-election was illegitimate and is applying intense economic pressure after recognising opposition leader Juan Guaido as interim president.

John Bolton, Trump’s national security adviser, advised in a tweet that “bankers, brokers, traders, facilitators, and other businesses” not to deal in any Venezuelan commodities that he alleged were being stolen by the “Maduro mafia.”

Some European oil traders had temporarily stopped dealing with PDVSA while their lawyers weigh whether it’s possible for non-U. S. entities to continue buying Venezuelan petroleum without breaking sanctions, people familiar with the matter said earlier this week.

Venezuela pumped 1.2 million barrels a day of crude in December, a decline of almost 50 per cent in four years, according to data compiled by Bloomberg. About 500,000 barrels a day of that output was exported to the US, but could potentially be diverted to other markets, if buyers are able to find ways to avoid using the American financial system.