how can I fix whistling,wheezing noises coming from a car engine?

I can hear whistling,wheezing noises coming from the engine on my vauxhall, TDI 2.0L LS hatchback, year of production 2002. The noises started a couple of months ago, I can hear the noises more and more. The noises does not subside when driving, they persist at the same level of noise. I can start the engine normally even if it is cold and have not driven it for a couple of days. The engine power does not subside when accelerating.
thank you for help.