Toronto-listed Pacific Rubiales, which has plays in Colombia, is paying some C$ 30 million ($29.29 million) for some 18% of CGX in an all-shares deal.

A private placement to pay for the stake is expected within a week and will bring Pacific Rubiales’ holding in CGX to around 35%.

Crucially the share purchase will give the former an option to participate in planned and wholly-owned wells belonging to CGX in Guyana.

If Pacific Rubiales takes up the options, it will fund 50% of the exploration costs and some seismic costs for a 33% share in each well in the Corentyne and Annex licences.

Pacific Rubiales chief executive Ronald Pantin said: "This is a great opportunity for the company to expand its investment in the highly prospective offshore Guyana oil play.

“Through our ownership in CGX, the technical services agreement and a direct earning option, the company will be participating in an exploration campaign in an offshore basin with analogous geology to West Africa and Brazil.”

Pacific Rubiales already has a large presence in Colombia as well as a stake in Peru and interest in Guatemala. However, the frontier region off the northeast coast of South America continues to attract interest from large international players.

Shares in CGX were up over 3% on Monday after news of the share purchase. They later saw a 33% intra-day gain.