A security association is reporting what it says is the first virus that can pass from a PC to a mobile device and then erase files.

The proof-of concept virus is not yet threatening users. It was sent to the Mobile Antivirus Researchers Association (MARA), which posted its findings on its Web site Monday.

MARA said the virus came with a text file that read, in part: "This is proof-of-concept code for educational purposes only. This virus closes the gap between handhelds and desktops, now it's one big world open to all."

The virus can be a nuisance in a couple of ways. On a PC, it will copy itself into the registry repeatedly as the machine is rebooted, according to the text file sent with the virus. As the virus replicates it can eventually hamper the machine's performance, it said.

The virus waits for a connection through ActiveSync, the Microsoft program that synchronizes data on a PC with a mobile device. It copies itself to the device, and if the device is running the Windows CE or Mobile OS, all files are erased in the My Documents directory, the note said. The virus was written using C# code with Visual Studio .NET 2003.

MARA said it will make the code available to antivirus companies and security experts. As of Tuesday morning, security vendors had not yet seen a sample of the code to comment on it, and Microsoft officials were not immediately available for comment.

Security experts have forecasted that mobile devices will increasingly be targeted by virus writers.