Sunoco Logistics Partners L.P. is set to buy its competitor Energy Transfer Partners — under fire over the construction of the Dakota Access oil pipeline — for about US$20 billion, AP reported Monday. Shares for both companies fell in the afternoon by 8-9 percent.

Sunoco Logistics has been found to spill crude more often than any company, with more than 200 leaks since 2010, according to a Reuters analysis of government data.

The lands of the Standing Rock Sioux Tribe sit a half mile south of the proposed route of the Dakota Access pipeline. The tribe fears the line could destroy sacred sites during construction and that a future oil spill might pollute its drinking water.

A tribal protest over the US$3.7 billion project drew broad support from other Native American nations, domestic and international environmental groups and Hollywood celebrities.

In response to the tribe’s objections, the U.S. government earlier this month called for a temporary halt to construction along a section of the 1,100-mile line in North Dakota near the Missouri River.