BP put around 10% of its oil and gas assets up for sale today as the firm looks to raise 30 billion dollars (£19.4 billion) over the next 18 months.

The lion’s share of the disposals will come from its exploration and production (E&P) division, which has a portfolio worth an estimated 250 billion dollars (£161.5 billion).

It has already begun the sale process with a seven billion dollar sale (£4.5 billion) to US firm Apache, but today’s announcement ramps up its original plans to make 10 billion dollars (£6.5 billion) in disposals to tackle the Gulf of Mexico spill.

But as well as strengthening its finances for the long haul ahead, BP is taking the chance offered by the crisis to push forward decisions to trim its portfolio through the sale of less attractive parts of the business.

The assets to be sold "on the basis that they are worth more to other companies than to BP" signals disposals of mature or declining production sources to specialist firms, while the company focuses on higher-growth areas such as the Gulf of Mexico, Egypt, Angola, Azerbaijan and Libya.

The E&P business has around 21,500 staff, of which 3,500 are UK-based in Aberdeen and Sunbury-on-Thames, Surrey. This will account for the vast majority of disposals, although speculation over a spin-off of its refining business regularly crops up and is dismissed by the firm.

Peter Hitchens, an oil analyst at Panmure Gordon, said: "They have been forced to do things that they would not normally do. What BP is actually saying is that they have got to decide where they want to do business.

"After the sales, production will take a long time to come back to where it was before but there will still be growth at the business - the focus is going to be on important areas like Brazil and west Africa.

He added: "It is one of the silver linings to come out of this crisis - it could be a real kick-start to the company."

BP may reshape its portfolio with a series of sales but the outlook is still far from plain sailing for the business.

The firm warned today that a six-month moratorium on deepwater drilling has been imposed by the US government, with similar actions potentially taken by governments elsewhere in the world.

A potential regulatory crackdown could also "materially impact the timing and cost" of exploration and production activity, it said.

Another huge uncertainty is how long it takes BP to rebuild its battered reputation following the spill.

"The incident has damaged BP’s reputation and brand, with adverse public and political sentiment evident. This could persist into the longer term, which could impede our ability to deliver long-term growth," the company said.