Black mould UNDER kitchen tiles

[imitsi]

Hi all

I just bought my first flat and I'm renovating it while living in it. Yesterday I was breaking the old kitchen floor tiles and I found that black hard substance, accompanied by a musty smell, so I think it's black mould. There was a boiler leak at least in the last 3 weeks, so it may have been caused by that (or at least it contributed).

Here's how it looks:
http://farm3.static.flickr.com/2215/218 ... 1200222584

As it's on a rough and uneven surface, and it's HARD, does anyone have any tips on how to remove it?

Also, is black mould safe to hoover?

Many thanks

John
Kingston upon Thames