Britney SpearsBritney SpearsThey've been married for 20 months and have their second child on the way.

But speculation is growing that Britney Spears and Kevin Federline are leading increasingly separate lives.

And there are even rumours that Britney has moved Kevin to a basement flat in their Californian mansion.

"The relationship has totally broken down," a source told the Daily Mirror.

"Britney desperately wanted it to work and still does for the sake of their family, but she has had enough...

"But rather than move out, she has ordered him down to a separate flat in their basement. They have, in effect, divided their house."

G Britney Kevin Federline Feb 06Britney with Kevin FederlineEarlier in the week, Britney had posted a poem on her website entitled Remembrance Of Who I Am, with the lines:

"No more chains that you gave me. My crown is back and it's way too high for you to be in my presence, especially my son."

Inevitably, there are whispers that it's all about Kev - and not long after the poem was posted on her site, it was removed and the site was down for maintenance.

Britney's spokesman refused to deny claims that the marriage is over - but neither did he confirm anything.