BP has said it wants to make its Aberdeen operation as efficient and simple as possible but declined to give any indication of how many jobs it might cut in the city.

The oil and gas giant said it expects to incur $1bn (£640m) restructuring charges over 15 months as it accelerates plans to shrink its global support operations following the recent sharp fall in the oil price.

BP gave details of the charge in an update in which it underlined the North Sea remains a core area for the firm.

The bulk of the provision will cover redundancy costs, under a programme that is expected to result in BP shedding thousands of jobs around the world.

Noting trading conditions have become tougher, chief executive Bob Dudley said: "We continue to seek opportunities to eliminate duplication and stop unnecessary activity that is not fully aligned with the group's strategy."

BP employs 84,000 people globally. It has 4,000 people working in and from its North Sea base in Aberdeen, including contractors.

Asked if the restructuring would impact on the Aberdeen operations, a spokesman said BP is looking at all its exploration and production operations around the world.

He said:" We are looking to ensure the operation in Aberdeen is as efficient and simple as possible just like every other part of BP."

The spokesman added that details of any job losses in the global E&P operation will only be disclosed as BP works through the rationalisation programme over the next five quarters, including the current period.

BP's comments may spark concern in Aberdeen amid fears the oil and gas industry could shed thousands of jobs in coming years.

On Tuesday an expert report predicted 35,000 jobs could go in the UK industry over the next five years as firms finish work on major projects in the North Sea. The estimate was made before taking account of the recent fall in the oil price.

After trading at $115 per barrel in June, Brent crude slipped below the $70 level for the first time in five years last week.

It fell to $65.84 in morning trading yesterday, while West Texas Intermediate crude fetched $62.63.

Experts say prices could fall much further following the recent decision by the OPEC club of major producing nations not to curb supplies. There is plenty of oil from US shale on the market and demand is slowing in places like China.

US giant Bank of America Merrill Lynch forecast that West Texas Intermediate could drop to $50 in the first half of 2015. It said OPEC's decision could result in much greater oil price volatility.

However, BP said it has a good track record of managing through cycles and has enough flexibility to withstand a period of low oil prices.

The company said it appraises potential investments at $60 per barrel and $80.

In a presentation led by BP's upstream chief executive Lamar McKay, the company described the North Sea as one of four key regional positions it expects to generate around half of the group's operating cash in 2018. The others are Angola, Azerbaijan and the Gulf of Mexico.

The company is investing billions of pounds developing the Clair Ridge field and revamping the Schiehallion development West of Shetland. Both feature in a list of major projects it expects to bring onstream by 2020 included in the presentation.

Fields like Clair could be in production for decades.

The company also included some North Sea fields, such as the recent Vorlich discovery, in a list of schemes that could drive growth after 2020.