1.8TDCi Turbo Squeal

[SJYates]

Can anyone offer any advice? Have a squeal on the turbo that only occurs on start up and acceleration. After 2-3min it disappears. Occurs both when then engine is cold and hot. Sounds just like the aux belt slipping but has that replaced and can now definitely source it to the turbo area.
No loss of power or excessive smoke shown at the moment.
It's a 1.8TDCi 125PS 80k
Thanks