CONCORD, N.H. – U.S. Rep. Carol Shea-Porter of New Hampshire has introduced a proposal aimed at oil pipeline activity between Portland and Montreal.

The amendment introduced Tuesday would protect environmental interests from being affected by pending legislation to approve the Keystone XL pipeline, which would carry 800,000 barrels of oil a day from Alberta across six U.S. states to the Texas Gulf Coast.

The Obama administration is considering whether to approve the pipeline.

There has been concern that the flow of a pipeline that now carries oil from Maine to Montreal could be reversed so that Canadian tar sands oil would flow through Vermont, New Hampshire and western Maine.

Critics say tar sands oil poses greater environmental and safety risks than conventional crude, but oil industry representatives disagree.

“Regardless of how one views the Keystone XL pipeline, my amendment simply clarifies that the expedited process made available for Keystone will not be used to short-circuit any environmental review for possible changes to the Portland to Montreal pipeline,” Shea-Porter said.

The amendment is co-sponsored by U.S. Reps. Annie Kuster of New Hampshire and Chellie Pingree of Maine.

In April, Shea-Porter joined members of Congress in sending a letter to Secretary of State John Kerry.

The letter requested a thorough investigation before the implementation of any proposal for pipelines in New Hampshire to reverse their flow and transport oil sands products.