Pete Doherty is ''haunted'' by never finishing a song with Amy Winehouse.

The Libertines frontman used to try to write with his late friend, but she was ''very, very critical'' of him, and their addictions frequently got in the way of their creativity.

He said: ''Invariable, whenever we got together to write, I was probably in no fit state either. But the way I remember it was she... I never really caught her at the right time.

''She was more interested in other things, not in actually getting any music done, which is strange because that's something people have accused me of as well.

''Whenever we used to get together to do music, she was always very, very critical of the new ideas I had. So we never ended up getting anything finished. I'm haunted by that.''

Pete - whose is donating the profits from his latest single, 'Flags of the Old Regime', to the Amy Winehouse Foundation - believes Amy felt ''trapped'' by her success.

He explained to NME magazine: ''She bought a brand new house in Camden Square, it was incredible, she had loads of great guitars in the basement and a huge music system. On her doorstep, she had all these horrible paparazzi. So she couldn't go anywhere.

''Blake [her husband] was in prison. She was just... She's got a lot time, she's been in a state of absolute despair. Fame had completely hemmed her in.

''I think her natural spirit was to be flying on melody and feeling. And yet she was caged. She was trapped...

''To make the money and get the wealth and power that comes with it, you have to sacrifice a lot of your personal liberties.''