The oil company BP has begun its latest attempt to halt the catastrophic oil leak in the Gulf of Mexico. It's used underwater robots to remove a cap that was placed over the fractured wellhead last month. A new cap will be fitted later. However, a permanent solution to stopping the oil - two relief wells - is still weeks away. Madeleine Morris reports.

The delicate operation to replace one cap with a more tight-fitting one could take up to a week. During that time, oil will flow unabated into the Gulf of Mexico. But BP and the US Coast Guard believe it's worth the potential environmental damage. The current cap is gathering only around half the gushing crude.