North America's tallest peak, Alaska's Mount McKinley, may have been taken down a notch.

An effort to update decades-old maps using aircraft-mounted radar technology showed the mountain, called Denali by locals, stands at 6,168 metres.

That's 25m shorter than an estimate of 6,194m from the early 1950s.

McKinley would still be more than 207m taller than the continent's second-highest peak, Canada's Mount Logan.

The discovery was made in 2011, after data from a 2010 flight was processed, but details weren't widely released until this week by Lt Gov Mead Treadwell.

The US Geological Survey says there are no plans to make the estimate McKinley's new official elevation. It says additional study and surveying would have to be done. There are no plans for such a survey.