VENEZUELAN prosecutors are set to charge hapless opposition stooge Juan Guaido over allegations that he would renounce claims to an oil-rich border territory in return for political support from Britain.

Venezuelan Prosecutor General Tarek William Saab confirmed on Friday that Mr Guaido is under investigation for illegally negotiating “the historical claim our country has on the territory of Essequibo” — a region controlled by neighbouring Guyana.

He claimed Mr Guaido has been engaged in “illegal negotiations, behind the back of the country” in exchange for “political support from the United Kingdom.

“The facts imply a crime of treason,” Mr Saab said.

Venezuelan Vice-President Delcy Rodriguez said the plot came to light when audio recordings emerged, reportedly capturing a US official urging Mr Guaido’s adviser Vanessa Neumann to “deliver the Essequibo” to Exxon Mobil and other multinationals.

In the recordings, alleged to have been made prior to Mr Guaido declaring himself interim president in January, a voice identified as Ms Neumann’s says that — after speaking with the British Foreign Office — the opposition would “drop the topic” of Venezuela's claim to Essequibo.

The 159,000 square kilometre territory is the subject of a long-standing border dispute between Venezuela and British Commonwealth member Guyana.

Last month Britain’s Defence Ministry was forced to deny allegations that it was building a military base in Guyana, on an island in the mouth of the Essequibo River, on the pretext of thwarting arms and drugs smugglers.

It followed claims by Russia’s Foreign Ministry that it had uncovered secret British plans to arm Venezuelan refugees across the border.

Britain is one of the countries that rushed to recognise Mr Guaido as Venezuela’s interim leader earlier this year.

Earlier this year, under pressure from US Vice-President Mike Pence, the Bank of England refused to hand over almost £1 billion of Venezuelan gold held in its vaults.

Ms Rodriguez said: “The criminal organisation headed by Juan Guaido has initiated concrete actions to illegally appropriate Venezuela’s assets, financial resources, Venezuelan gold, Venezuelan debt — to enrich themselves and to serve transnational interests.”

In April Venezuela’s Constituent Assembly lifted Mr Guaido’s immunity from prosecution. But while he has remained free he has continued to try to orchestrate a coup to oust President Nicolas Maduro.

He already faces several other charges, including “usurping the functions of the president.”