HOUSTON, March 8 (Xinhua) -- Concerns have been raised about the impact of imposing tariff on imported steel which can result in much high cost in energy infrastructure, Lisa Murkowski, U.S. Senator of Alaska, told Xinhua on Friday.

U.S. President Donald Trump on Thursday formally signed proclamations to impose a 25 percent tariff on imported steel and 10 percent on aluminum.

Commenting on the White House decision at CERAweek, Murkowski, also the chairman of the U.S. Senate Energy and Natural Resources Committee, said there has been concern that the tariff will considerably increase the cost of energy infrastructure construction.

"This is something that has generated more of the concern when you think about what these tariffs may do to the cost of a mega project like the Alaska LNG (Liquefied Natural Gas) line," she said.

Murkowski was talking about a mega-project that involves an 800-mile (about 1,300 km) gas pipeline from the North Slope to south Alaska, where the gas can be super-chilled into LNG and loaded into oceangoing tankers.

She said there has been initial calculation that with the steel tariff imposed, up to 500 million U.S. dollars will be added on to the Alaska LGN pipeline.

"When you think of extraordinarily cost increase, the impacts of the tariffs to the overall cost is a concern and is considerable," she added.

CERAWeek, which kicked off on Monday and ended on Friday, is an annual energy meeting held by the London-based information company IHS Markit featuring prominent speakers from energy, technology and financial sectors.

This year's meeting was attended by more than 3,000 guests from over 50 countries and regions.