The chief executive of BP hailed the oil giant’s “best year in exploration for a decade” as he waded into the row over Scottish independence and disclosed a further $200m (£123m) of charges for 2010’s Gulf of Mexico oil spill.

Unveiling a 22pc fall in full-year profits, Bob Dudley sounded a more optimistic note for 2014, buoyed by six projects coming on stream this year, including Chirag Oil in Azerbaijan and the Mars B rig in the US Gulf that have already started to pump.

“2010 was the year of crisis, 2011 a year of consolidation, 2012 was about starting to hit milestones and 2013 we started to build momentum,” said Mr Dudley.

He added: “Right now, we are confident that we can hit our operating cash flow target of $30bn – it looks a stretch from $21bn [last year] but we are on target.”

Underlying replacement cost profits – stripping out fluctuations in the value of inventories – fell from $3.9bn to $2.8bn in the fourth quarter, marginally ahead of consensus expectations. Full-year profits on the same basis dropped from $17.1bn to $13.4bn.

BP shares rose 0.2 to 473.8p.

Part of the fall was down to a plunge in downstream profits over the fourth quarter, from $1.4bn to just $70m, hit by a “significant” fall in refining margins and the sale of two big US refineries – Texas, home of 2005’s fatal fire, and Carson.

But group profits were also hit by BP’s $38bn disposal programme since 2010 to help fund the clean-up and litigation costs for the Gulf spill, which left 11 dead. BP has now upped its total provision by $200m to $42.7bn, with roughly $150m of the increase to fund its own legal costs. They now top $1bn.

Mr Dudley said the assets sold, accounting for about $5bn of earnings, spanned “half the platforms, half the operating facilities, half the pipelines that BP had but only 10pc of the reserves” – a programme that has produced a more focused, “simpler company”, where it is “simpler to manage risks”.

BP has since outlined plans to sell another $10bn of assets over the next two years, with the intention of using the proceeds to fund share buy-backs. But the group also has a growing pipeline of new projects and expects an underlying rise in production this year.

Longer-term that should be boosted by a step-up in exploration. Mr Dudley said that last year: “We drilled 17 exploration wells – two years ago we were drilling about eight. And we had seven commercial discoveries.” They include discoveries in Angola, Brazil, Egypt, the Gulf of Mexico and India.

Mr Dudley added that the group’s decision to take a 19.75pc stake in the Kremlin-controlled Rosneft, rather than continue a fractious relationship with its four oligarch partners in the former TNK-BP joint-venture, would prove “a very significant transaction”.

Rosneft generated net income of $1.1bn in the fourth quarter versus just $200m from its former TNK-BP joint-venture, while its production has returned BP to a producer of more than 3m barrels of oil equivalent per day. While, Mr Dudley has no current plans to team up with Rosneft to explore the Russian Arctic, he said: “We will likely at some point set up some small joint-ventures with Rosneft onshore.”

Capital expenditure in 2013 was $24.6bn, in line with guidance, and BP said it expected to spend around $24-$25bn this year and stay within a $24-$27bn range through to the end of the decade.

Cash-flow is expected to be boosted by about $1bn this year by the return to service of the modernised Whiting refinery near Chicago.

Mr Dudley said he was well aware of shareholder pressure to maximise returns from spending, not least in an era of flat or falling energy prices, thanks to the US shale revolution.

“We want to be a shareholder friendly company. People generally regard oil and gas as businesses that put lots of money in to generate lots of cash and then put that right back in to big projects, with nothing left for shareholders. I’ve heard this for several years. Our message to employees is spend the company’s money as if it was your own.”

Jonathan Jackson, head of equities at Killik & Co, said: “The underlying business is now more focused and has the potential for strong growth from exploration and production.” But he added: “The main driver of the share price remains newsflow regarding the Gulf of Mexico oil spill.”

BP is still awaiting a final US court decision over whether it was considered grossly negligent for the Deepwater Horizon accident – a decision that could add $20bn to the final bill because it would bring cash penalties under the Clean Water Act. Mr Dudley disputes any charge of gross negligence while continuing to fight some compensation claims that he said amounted to “potential fraud” as there was no evidence the claimants were affected by the spill.

Of BP’s own rising legal bill, he said: “The US is a very litigious society, we don’t have a choice.”

He also dealt a blow to the Scottish independence dreams of SNP leader Alex Salmond. Noting that “we have a lot of people and assets in Scotland”, he said: “It will undoubtedly add some cost to us”. He added “I think Great Britain is great and for me personally it would not seem like an advantage”.

BP is paying a fourth quarter dividend of 9.5 cents per share, up 5.6pc.