Premier Oil's CEO said the company has saved about US$250 million thanks to the depreciation of the British pound following the country's vote to leave the EU.

Premier Oil, which on Aug. 18 announced a return to profit in the first half of the year despite weak oil prices, earned the windfall from investments denominated in sterling, lower decommissioning fees also in sterling, and a higher value for its US$120 million acquisition of E.ON's North Sea assets.

The pound has fallen to the lowest level against the dollar in more than 30 years since Britain's Brexit vote in late June.

"A weaker sterling exchange rate means it costs us less dollars to pay for our investments," Premier Oil's CEO, Tony Durrant, told Reuters.

Premier Oil, which is a heavy investor in Britain's North Sea, also raised its full-year output target by 4% on Aug. 18 after better-than-expected output, mainly from its British fields. It now expects full-year output of 68,000 barrels per day (Mbbl/d) to 73 Mbbl/d, up from the previous range of 65 Mbbl/d to 70 Mbbl/d.

Durrant said next year's average daily production could be about 10 Mbbl higher, as Premier's US$1.8 billion North Sea Catcher project comes onstream in 2017.

"Premier should be able to deliver a record production rate of over 100 kboe/d [thousand barrels of oil equivalent per day] in our view. This would be a positive psychological hurdle to pass," said analysts at Jefferies, who recommend a Hold rating on the stock.

The London-listed firm, whose operations stretch from the Falkland Islands to Indonesia, returned to profit in the first six months of the year, reporting profit after tax of US$167 million compared with a US$375 million loss in the same period last year.

Premier Oil's shares rose more than 2%. They have risen more than 60% since the start of the year, compared with a 9% rise in the oil and gas company index over the same period.

The company's share price more than doubled in February following its acquisition of E.ON's North Sea assets.

Premier Oil said refinancing discussions with lenders would continue until around the end of September, when terms will be disclosed. Premier Oil said debt levels stood at US$2.6 billion at the end of June, higher than a year ago but down from the end of the first quarter.