By NBF News

BP has begun a test on the leaking Gulf of Mexico oil well to see if flow can be stopped.

The test – which had been due to start on Tuesday – involves closing three valves on a cap on top of the well.

BP expects that no oil will be released from the well during the test, which will check the pressure inside the wellbore for up to 48 hours.

This would be the first time the flow has stopped since the explosion on the Deepwater Horizon rig on 20 April.

But BP is stressing that even if no oil escapes for 48 hours, that will not mean the flow of oil and gas has been stopped permanently.

The pressure testing is necessary to check the strength of the well. If the pressure within the cap on top is low, that could indicate oil is leaking out further down the well.