BP Wrestles with Oil Spill Hitch in Gulf of Mexico

A massive effort to contain what threatens to become an environmental catastrophe has been under way since 20 April, when an explosion killed 11 workers and led to the eventual sinking of the Deepwater Horizon rig, 50 miles (80km) off Louisiana.

A sheen of oil began washing ashore on the Chandeleur Islands chain last week, and crews have been laying inflatable booms, spraying chemical dispersants and setting fire to the slick to try to protect local wildlife, reports BBC News.

Although the Deepwater Horizon was operated by Transocean, it was leased by BP, which is responsible for cleaning the 3.5 million gallons that have so far leaked out of the well below, creating a slick covering about 2,000 sq miles (5,200 sq km).

The 98-tonne concrete-and-steel funnel lowered 5,000ft (1,500m) to the seabed had been BP's best hope to contain the main leak while it attempted to stop it altogether by drilling relief wells nearby. But a build-up of gas hydrates - crystalline water-based solids resembling ice - inside the device blocked the exit at the top, and it had to be put aside until engineers could decide what to do.