Why does my washing machine smell like wee?!

[glitterbean]

Machine is about two years old but over the last couple of days there has been the distinct smell of wee coming from it, mainly when it's on! Any ideas what it could be and how to get rid of it?

Try running a dishwasher tablet in the drum through on a hot wash.

Did you get it sorted OP? I'm having the same problem.
Will try Dame suggestion.