(Bloomberg) -- Top UK oil and gas producers complained that there’s still little clarity on the government’s plans for taxes and permits for North Sea drilling, making investment decisions difficult.

“We do think that there are opportunities in the North Sea, but these are not really going to be commercially viable if we don’t see the stability of economic and regulatory landscape,” Hebe Trotter, vice president for global government relations at Harbour Energy Plc, said at the UK Parliament’s Scottish Affairs Committee session on Wednesday.

There are still a lot of economic opportunities even in the mature North Sea basin, but the region “can’t compete with other basins which we operate in” because of this uncertainty, said Louise Kingham, BP’s head of UK and senior vice president for Europe.

Both the current Labour government and previous Conservative government raised taxes on North Sea oil and gas producers. This year, the government will consult with the industry on the fiscal regime beyond 2030, when a windfall tax called the Energy Profits Levy ends.

A recent court ruling forcing the Rosebank and Jackdaw projects to reapply for environmental permits has added to the uncertainty.

Following the tax increase, the North Sea Transition Authority cut its forecast for investments and production in the North Sea in the coming years.

“There are plenty of other countries where we operate in that have more favorable fiscal environment,” said Trotter. “Every pound, if decided not to be spent here in UK, is essentially fewer jobs, less money in terms of tax receipts.”