Image caption Rain could carry oil sheen towards a nearby lake

The US state of Arkansas has launched an investigation into the rupture of an Exxon Mobil oil pipeline that spilled thousands of barrels of crude.

Attorney General Dustin McDaniel asked the company to keep all documents pertaining to Friday's spill.

The rupture in Mayflower prompted the evacuation of 22 homes, with police enforcing a blockade around the spill.

The spill has renewed debate over a proposal to build another pipeline from western Canada to the US Gulf Coast.

Also on Tuesday, the federal Pipeline and Hazardous Materials Safety Administration issued an order preventing Exxon Mobil from restarting operations on the affected segment of the pipe until it had signed off on the repair work.

In the wake of Friday's release of between 3,500 and 5,000 barrels of oil from the Pegasus pipeline, black crude was seen soaking lawns and streaming down residential streets in the community north of the state capital, Little Rock.

'Future litigation'

"This incident has damaged private property and Arkansas's natural resources," Mr McDaniel said. "Homeowners have been forced from their homes."

He said the request that Exxon Mobil keep records on the spill was the "first step in determining what happened and preserving evidence for any future litigation".

The oil company has said it will co-operate with any investigation.

Exxon Mobil says it plans to dig up and replace the broken part of the 65-year-old line that runs from the state of Illinois to Texas.

But rain forecast for Tuesday afternoon could hamper the clean-up by carrying oil sheen towards nearby Lake Conway, a popular destination for bass, catfish, bream and crappie fishing.

Local responders have built barriers of rock and dirt to stop the oil from contaminating the lake, and Exxon Mobil put booms into the lake as a precaution.

The oil company said it was putting together a plan to enable residents return home. Until then, Mayflower police were accompanying them as they retrieved personal belongings from their houses.

Separately, Canadian oil company TransCanada has proposed building a 1,700-mile (2,735km) pipeline called Keystone XL to carry crude from Alberta, Canada's tar sands region to refineries in Texas.

The project has encountered stiff opposition from environmental groups.