The National Energy Board has asked Imperial Oil and other backers of the Mackenzie Valley gas pipeline to update the project's economic feasibility assessment and construction schedule.

In a letter dated Monday, the federal energy regulator said the companies involved in the proposed Northwest Territories pipeline are using information that is "out of date and should be updated."

The request came after Yellowknife-based social justice group Alternatives North demanded that the pipeline consortium, led by Imperial Oil, provide new data related to economic feasibility and natural gas market demand.

The group claims that demand for natural gas has changed significantly since the pipeline project's economic figures were last updated in 2007.

Imperial Oil had argued that the National Energy Board is not in a position to decide whether the pipeline would make economic sense, as that decision would be up to the consortium itself.

If approved, the 1,220-kilometre pipeline would run from Inuvik, N.W.T., through the territory's Mackenzie Valley to northern Alberta, where it would connect with southern markets.

Other partners in the pipeline consortium include Royal Dutch Shell Plc., ConocoPhillips, Exxon Mobil Corp. and Aboriginal Pipeline Group.

Imperial Oil now has until March 15 to file new market demand and economic feasibility figures, as well as provide a new project schedule.

Officials with the Calgary-based company said they would comply with the board's request, but called the additional work a "significant undertaking."

The new information will be subject to cross-examination during a National Energy Board hearing slated to be held in Yellowknife on March 29.