iPhone locked due to illegal activity

Not sure what has happened. This morning when I went to launch Safari on my iPhone, it went to a URL "security-breach.net, and kept flashing back and forth with my printer program. I can not enter any data, or do anything to Safari to make it work. The only thing I can do is shut it down. I'm assuming it is some kind of virus.

The screen lists a Support number (****)

The error message says:

"Attention!

Your device has been locked due to detected illegal activity! Immediately call Apple Support to unlock it.

We're here to help."

What is this, because I don't believe it is an actual Apple alert. Assuming it isn't, how do I deal with it.

Thank you.

[Edited by Host]