Annoying whistle or squeal

Getting annoying whistle or squeal sound, and need some advice.
Noise is happening after a run of more than 10 miles, and I seem to have narrowed it down so was wondering if anyone knows what it is.
Squeal only happens when idling or stopped.
When stationary for about 2 minutes, it stops. A touch or revs and it stops only to start again when the revs drop again.
Turning steering to full lock makes it start again, only to stop after a couple of minutes.

So far, I have narrowed it to only be occurring when vehicle is warm, and idling.
When steering is turned to lock it starts again.
Revs make it stop, idling makes it start.
It stops on its own after idling for about 2 minutes.
Noise is high pitched, and quite loud.

This leads me to believe it is something steering related, maybe the pump? Can anyone confirm or has anyone had this before?

Many thanks guys. Ps I have done a search.

rule it out, check exhaust manifold bolts on piston nearest rad, they may be sheared, missing

jrmroxx said:

rule it out, check exhaust manifold bolts on piston nearest rad, they may be sheared, missing

Click to expand...

Would they cause such a noise?

300Tdi? Could be aux belt, the PAS pump is working hard on idle. Try this........

http://www.landyzone.co.uk/lz/f72/300tdi-squeeling-belt-penny-trick-171197.html

Could be a slightly loose or noisy pulley on the pump or alternator

blue beasty said:

300Tdi? Could be aux belt, the PAS pump is working hard on idle. Try this........

http://www.landyzone.co.uk/lz/f72/300tdi-squeeling-belt-penny-trick-171197.html

Click to expand...

Will have a look at that.
So it could be the belt making the noise? It's with it starting after going to full lock that made me think it was the pas. I'll try the penny trick.