A bipartisan deal between Labor and the Coalition on landmark laws that will give law enforcement agencies increased powers to access encrypted communications appears to be on the rocks.

The opposition is now promising to pursue further changes in the Senate to the bill which would allow intelligence and police agencies to compel tech companies to help them hack encrypted messages.

The laws looked set to pass the parliament on Thursday, after the government put forward amendments that were supported by Labor, giving tech companies a right to challenge orders from spies.

But in a surprise development on the afternoon of the last sitting day of 2018, shadow attorney-general Mark Dreyfus said the 50 pages of amendments did not do enough to reflect the intelligence committee’s recommendations.

Labor wants the two-person review panel – consisting of an ‘expert’ with top-level security clearance and a retired senior judge – to be given more teeth.

Earlier, Labor MPs told Parliament the bill was still flawed and would need to be “fixed” in 2019.

Opposition MP Ed Husic said there should be reporting obligations so agencies would need to reveal how many times they were using the new powers, as well as stronger judicial oversight.

Mr Dreyfus said the new definition of ‘systemic weakness’ was still too vague.

The bill bans security agencies from asking companies to build a “systemic weakness”, but did not previously define what that meant.

Tech companies have lobbied for a definition that makes it clear they cannot be forced to build long-term, latent “backdoors” in their tech that could later be discovered by cybercriminals or hostile foreign states.

The new definition says a “systemic” vulnerability is one that affects a “whole class of technology”.

“What does that mean?” Mr Dreyfus asked in the chamber.

Labor passed the government’s amendments in the Lower House, but said it would pursue more changes in the Senate this afternoon.

Manager of opposition business Tony Burke said the opposition would stay at parliament as long as necessary.

“We are not afraid of the parliament sitting, we’re happy to stay here for as long as it takes today. We don’t need to clock off early.”

He said the Senate amendments would “properly reflect” the cross-party Intelligence committee’s 17 recommendations.