Ascent Resources said it remained hopeful of obtaining two key permits for its Petisovci field in Slovenia but would pursue legal action if they weren't granted.
One of the permits would allow the company to install a gas processing facility, while the other would allow it to re-stimulate wells to enhance their production.
Chief executive Colin Hutchinson said the pace of progress to date had been 'frustratingly slow'.
'As we continue to follow the process and provide those responsible for making the permitting decision with all of the information they require, based on the unarguable benefits for the country I remain hopeful the permits will be awarded in due course,' he said.
At 3:01pm: (LON:AST) Ascent Resources PLC share price was -0.03p at 0.28p