The Prime Minister is signalling the Government is open to making changes to its foreign fighters legislation.

A Parliamentary Committee is due to report back on the Bill tomorrow.

It's faced widespread criticism of such measures as extending the powers of the SIS.

John Key says they're listening to the concerns of submitters and are engaging in good faith with other political parties.

He says they have an open mind and it's entirely possible changes will be made before the Bill is passed into law.