TransCanada Corp. is seeking regulatory approval to begin construction of a pipeline that would help feed a proposed liquefied natural gas export terminal on B.C.'s north coast even though a final decision has not yet been made whether to build the terminal.

The Calgary-based company has conditional federal and provincial approvals for the North Montney Mainline, but they are subject to a positive financial investment decision for the proposed Pacific Northwest LNG project on Lelu Island near Prince Rupert, B.C.

TransCanada says the modified proposal filed with the National Energy Board would allow it to move forward with construction of the majority of its North Montney Mainline project at a cost of $1.4 billion ahead of that decision.

The proposed NMML project would include 301 kilometres of pipeline and related facilities that will connect with an existing pipe about 35 kilometres southwest of Fort St. John, B.C.

The LNG terminal is primarily backed by Malaysia's national oil and gas company, Petronas, which has yet to make a final investment decision for the Pacific Northwest LNG project.

TransCanada says that it's seeking regulatory approvals that would allow it to begin construction on the pipeline in the first half of 2018 and bring it into service over a two-year period beginning in April 2019.