The oil slick from the ruptured Deepwater Horizon rig in the Gulf of Mexico, US, has reached the Louisiana shore.
US officials have confirmed that a sheen of oil has washed up on Chandeleur Islands, an important breeding and nesting area for birds.
News that the oil has come ashore came as BP workers began lowering a containment dome on to the seabed, in the hope that it will help close the leak spilling over 5,000 barrels of oil into the sea every day.
The 100-tonne containment vessel is designed to collect as much as 85% of the oil pouring into the Gulf and funnel it up to a tanker.
It could take several hours to lower it into place by crane, after which a steel pipe will be installed between the top of the box and the tanker.
It is expected that the whole structure will be in operation by Sunday.
The Transocean-owned Deepwater Horizon rig exploded on 20 April, with 11 workers missing, presumed dead.