Every time I flush my toilet there is a loud creaking noise which appears to be getting worse. How do I fix this?

Everytime i flush my toilet there is a loud creaking noise which appears to be getting worse. How do i fix this?
This "loud creaking noise", does it occur as the tank is filling or as the flush goes down? Back to you. Tom

This "loud creaking noise", does it occur as the tank is filling or as the flush goes down? Back to you. Tom
Hi Tom, Thanks for getting back to me. The noise seems to happen for both but is much worse as the tank is filling back up.