Labour says it has secured concessions to urgent counter-terrorism laws including a shorter period of 24 hours for warrantless surveillance of terror suspects.
Leader Andrew Little said his caucus would decide its position on the Countering Terrorist Fighters Legislation Bill this morning, but it was now likely Labour would support it.
The Foreign Affairs select committee will report back on the bill to the House this afternoon.
Mr Little said the most controversial provision to allow spies to monitor suspects without a warrant would now apply for 24 hours instead of 48 hours and could only be used for anti-terror activities - not for the Security Intelligence Service's broader activities.
Prime Minister John Key yesterday signalled this was one area Government was prepared to change to get cross-party support.