A possible backdown by Prime Minister John Key may see the hearings on changes to intelligence spying opened up to the public.

The Security Intelligence Service Amendment Bill was introduced to Parliament this week and Mr Key had previously said he would block any attempt to hold the hearings in public.

But after meeting the intelligence and security committee he said he would reconsider the issue.

The bill aims to update the 41-year-old law on how the SIS is granted intelligence warrants.