BP says it is still a fortnight away from permanently sealing its stricken Gulf of Mexico oil well, as it reveals clean-up costs have soared to $8 billion. 

The British oil major says it is hopeful its relief well will intercept the ruptured MC252 well in mid-September depending on the weather conditions.

It initially capped the well on 15 July - three months after disaster first struck - but removed the cap on Thursday in order to replace the failed blow-out preventer with a working safety device.

The FTSE 100-listed group says it is on standby to resume drilling the relief well, which has so far reached depths of 17,909 feet.

Meanwhile, it says that no new volumes of oil have been found on the water's surface since 21 July, following its shut-in operations.

Throughout the response, skimming operations captured over 826,000 barrels of oil liquid.

The spill was triggered after an explosion occurred on the Deepwater Horizon rig in April, killing 11 workers and causing the subsequent sinking of the rig.

In the four-and-a-half months since the explosion, BP has seen its clean-up costs rocket to $8 billion and exceed $2 billion in the last month alone, as it battles to plug the well.

That figure includes costs related to its spill response, containment, relief well drilling, static kill and cementing, grants to the Gulf States, claims paid and federal costs.

Since the claims process was transferred to the Gulf Coast Claims Facility, headed up by Ken Feinburg, BP has paid out $38.5 million covering 4,900 claims. Prior to this, it made 127,000 payments totalling some $399 million.

Today's update comes just 24 hours after BP told federal regulators that the disaster had spurred improvements in relief wells, unmanned submarines and other technologies, which could go some way towards combating future offshore disasters.

In a 74-page report, it says its attempts to halt the oil spill had shown which methods were effective and 'these new capabilities can be an integral part of an improved planning and response regime for the industry, government and responders'.

Its shares rose 0.22 per cent to 393.43p.