Yet its profits were still more than double analysts' estimates, thanks to its refining and trading businesses which offset lower oil prices.

The oiler's chief financial officer Brian Gilvary said in a conference call that the 800 added to the 2500 BP has cut since the end of 2012 to the end of 2014 across its upstream, downstream and corporate units.

"It's quite a painful process that we're going through," he said. "It's a journey that we've been on for close to two years. We're starting to see the benefits of that in lower costs across both of the major businesses and corporate functions."

BP posted a $2.6 billion ($A3.24 billion) profit in the March quarter, compared to $3.5 billion in the same period last year, while its revenues dropped from $93 billion to $55 million.

Gilvary said BP made $350 million more from oil trading than in a "normal" quarter, using an extra $1.4 billion in the quarter to capitalise on a market structure known as contango, where oil for future delivery is costlier than near-term contracts.

BP's profit adjusted for one-time items and inventory changes plummeted 19% from a year earlier to $2.6 billion, which beat the $1.2 billion average estimate of 12 analysts surveyed by Bloomberg.

Gilvary also said the super-major saw "potential opportunity" for buying assets this year.

The cancellation fees for its Gulf of Mexico rigs contributed to a Q1 loss of $545 million for its US upstream business, even as it upped production and lowered costs. Income for its upstream operations outside the US dropped from $3.7 billion to $1.1 billion.

BP CEO Bob Dudley said the company was "resetting and rebalancing" to meet the challenges of "a possible period of sustained lower prices".

"Our results today reflect both this weaker environment and the actions we are taking in response," he said.

"We are continuing to progress our planned divestment programme, we are resetting our level of capital spending, and we are addressing costs through focusing on simplification and efficiency throughout BP."

BP is on track to divest a further $10 billion of assets by the end of the year, with the current total currently at $7.1 billion, including last week's announcement to sell BP's interest in the CATS business in the UK North Sea.

Organic capital expenditure in the first quarter was $4.4 billion and Dudley confirmed BP's "reset expectation" of $20 billion total organic capital expenditure for 2015.

"We will also look to take advantage of any opportunities presented by the lower price environment to further reduce capital expenditure or costs," he added.

Operating cash flow for the quarter was $1.9 billion compared with $8.2 billion a year earlier. The quarter's operating cash flow included a working capital build of $2.5 billion. At the end of the quarter BP's net debt was $25.1 billion, equivalent to a gearing level of 18.4%.

At the end of the quarter, the total cumulative pre-tax charge for the Gulf of Mexico oil spill was $43.8 billion.

BP said an additional charge of $332 million was taken in the quarter due mainly to additional business economic loss claims.

This overall charge does not include any provision for business economic loss claims that are yet to be received, processed or paid - except where an eligibility notice has been issued and is not subject to appeal by BP within the claims facility, BP said.

At the end of the quarter the aggregate remaining cash balance in the Trust and qualified settlement funds was $4.3 billion.