OTTAWA (Reuters) - Canada, looking to shore up its defense of the Arctic, is moving ahead to acquire up to 12 submarines and has started a formal process to meet with manufacturers, the defense ministry said on Wednesday.

Canada updated its defense policy this year with a focus on protecting the Arctic and dealing with challenges from Russia and China. The procurement of submarines is a critical step in implementing that strategy, the defense ministry said in a statement.

Citing global warming, Canada says the Arctic Ocean could become the most efficient shipping route between Europe and East Asia By 2050, thus raising the need to bolster maritime security.

"As the country with the longest coastline in the world, Canada needs a new fleet of submarines," Defence Minister Bill Blair said in the statement.

After meeting manufacturers, the ministry in autumn will post a formal request for information on the procurement, construction, delivery and operational capabilities of potential bidders.

Canada currently has a fleet of four submarines that the ministry said was growing more obsolete and expensive to maintain. The new fleet of submarines will be conventionally powered and capable of operating under ice.

Ottawa has been under U.S. pressure to boost defense spending to meet the 2% of gross domestic product agreed to by NATO allies in 2023. The defense policy update in April outlined billions more for the armed forces, including money for submarines, to take spending to 1.76% of GDP by 2030, up from the current 1.4%.

Canadian broadcaster CTV News, citing unidentified government sources, reported on Wednesday that Canada would unveil a plan on Thursday on how to reach its NATO commitment to spend two 2% of its GDP on defense.

The defense ministry did not immediately respond to a request for comment on the report.

(Reporting by Ismail Shakil in Ottawa; Editing by David Gregorio)

By Ismail Shakil