The loan is provided by an institutional family-office investor based in the Bahamas The expansion of the facility will see immediate additional cash inflow of £1.8mln.
The company can elect to access the remaining balance in four committed instalments through April to July 2020.
In a statement, the group said the estimated cost of drilling its 100%-owned and operated Perseverance #1 well, targeting recoverable prospective resources of up to 1.4 bn barrels of oil, is between US$25mln and US$30mln.
The company's overall funding capacity for its strategy is now approximately $45mln.
“Materially increasing the size of the facility with the same investor on an immediate, unconditional basis is, in and of itself, a tremendous boost for the project,” said Bahamas' chief executive Simon Potter.
“Moreover, for the company to achieve this in the face of the decline in oil price and the global adverse impact of the Covid-19 virus is an enormous vote of confidence in the company, our planned drilling activity and the robust nature of our prospects.
"Notwithstanding current turmoil in the world's financial markets and the disruption associated with the Covid-19 virus, including interruption to our drilling schedule, the project team remains together, focused and intent on delivery. I look forward to updating shareholders further over the coming weeks."