It may take at least two weeks to plug the oil leaks from the Gulf Coast oil rig, according to a British Petroleum (BP) official on Monday.

Photo shows an explosion and fire on an offshore drilling platform off Louisiana's coast Wednesday. [Photo: Chinanews.com]

The leaks were discovered Saturday in the riser, the long pipe that extended from the wellhead to the drilling platform. BP was leasing the drilling platform and is responsible for the cleanup under U.S. federal law. Eleven crew members of BP were still missing and presumed dead.

The flow of oil from the leaks into gulf waters is about 42,000 gallons (about 159 cubic meters) a day. The cause of the explosion was still unclear, according to authorities, a New York Times story said.

Efforts to have robotic submersibles activate a shutoff valve have so far failed, and BP is now building a dome meant to capture the oil and then pipe it up to the surface.

However, that could take two weeks, according to Doug Suttles, BP's chief operating officer for global exploration. "That system has been deployed in shallower water," he said, "but it has never been deployed at 5,000 feet (about 1.52 km) of water, so we have to be careful."

The oil spill was covering an area in the Gulf of Mexico of 48 miles by 39 miles at its widest points, U.S. Coast Guard officials said Monday afternoon. A rig 10 miles away was evacuated earlier in the day as it became surrounded by a growing sheen, according to a report on MSNBC.com.

Officials determined through weather patterns that the sheen of oil and water would remain at least 30 miles from shore at least until Tuesday. But states along the Gulf Coast have been warned to be on alert. The U.S. federal response team said they would do whatever they could to make sure the leak is plugged.

An even longer-term option would be to drill one or two wells nearby that would reroute the oil. A drilling rig was expected to arrive at the site Monday night in anticipation of that strategy.

Officials are monitoring the environmental effects of the spill by boat and planes.