Some versions of Nokia's Lumia 800, the first flagship smartphone from the Finnish company using Microsoft Corp's Windows Phone operating system, have a software glitch that drains the batteries.

We can now confirm that, while the battery in the devices is fine, in some variants a software problem is preventing the phone from accessing the full battery capacity, a company spokesman said.

He said the problem will be fixed in early 2012 with a planned, wider software update.

Once this update is applied customers should experience much better battery life, he said.

The Lumia 800 is the first Nokia smartphone to use Microsoft software, the platform the Finnish firm has bet its future on.

Since Nokia unveiled the Lumia 800 the stock has dropped almost 30 percent, in part due to fears of poor sales because the device has received positive reviews, but limited interest from consumers.

(Reporting By Tarmo Virki; editing by Andre Grenon)