Federal Labor will pursue significant changes to a controversial medical evacuation bill to allay security agency fears it will encourage asylum seeker boats to resume coming to Australia.

Key points: Labor seeks changes to medical evacuation bill amid national security concerns

Labor seeks changes to medical evacuation bill amid national security concerns The Coalition says the proposed bill will encourage asylum seekers

The Coalition says the proposed bill will encourage asylum seekers The Opposition insists its changes will eliminate the chances of restarting people smuggling

ASIO director-general Duncan Lewis and Home Affairs secretary Mike Pezzullo met with Labor and urged Opposition Leader Bill Shorten to show great caution in any retreat on the current border protection settings.

The ABC understands that in an hour-long session, the high-ranking officials told Mr Shorten, his deputy Tanya Plibersek and shadow immigration spokesman Shayne Neumann to avoid supporting measures that would serve as a "pull factor" for people smugglers.

Declassified ministerial advice dated December 11, 2018 shows the Home Affairs Department warned the existing bill "removes the third pillar – regional processing" if passed unamended.

The bill, which passed the Senate last year, proposes giving doctors a greater say in evacuating asylum seekers from Nauru and Manus Island for treatment or assessment.

Home Affairs said this would allow "most of the 1,000 individuals" on Manus and Nauru transferred to Australia within four weeks of royal assent.

It is understood Labor will consider broadening the definition of "security" in the bill to give the minister a broader discretion to deny transfer of asylum seekers, perhaps by extending it to people who have committed serious crimes or by inclusion of a "character test".

Labor will consider extending the timeframes in the bill, replacing the 24-hour periods for review and decision-making to "as soon as practicable".

The Opposition will also consider restricting the medical evacuation bill to the existing cohort of asylum seekers on Nauru and Manus to eliminate any chance the bill will serve as a "pull factor" for new boats.

Shadow cabinet is meeting this afternoon, with Labor MPs and senators to hold a caucus meeting this evening.

If agreed to by caucus, the changes would have to be negotiated with crossbench senators, some of whom are described as being "receptive" to the proposal.

Prime Minister Scott Morrison today said he would enter no negations on the bill, saying it was "superfluous" and would unwind offshore processing.