The EU reached a landmark preliminary agreement on Wednesday to reform its laws on asylum-seekers and irregular migrants.

Here are the main changes, agreed after lengthy negotiations between EU member countries and the European Parliament that still must be formally adopted:

- Border filtering -

The new EU Asylum and Migration Pact will see migrants irregularly entering the EU undergo identity, health and security checks, and have biometric readings of their faces and fingerprints recorded, which can take up to seven days.

Children will get special treatment, and member countries are to have independent monitoring mechanisms in place to ensure rights are upheld.

The procedure aims to determine which migrants should receive an accelerated or normal asylum application process, and which ones should be sent back to their country of origin or transit.

- Streamlined vetting -

Asylum-seekers with lower chances of receiving protection status -- defined as those coming from countries whose nationals' asylum applications are, on average, rejected in at least 80 percent of cases -- will be processed faster. Nationals from countries such as Tunisia, Morocco and Bangladesh figure in that category.

Their streamlined applications would be processed in centres not far from the EU's "external borders" -- meaning mostly land frontiers and ports, but also airports -- so they could be quickly sent back if their request is judged to be unfounded or inadmissible.

This would require using detention centres, though alternative measures can be used, such as confinement in residences. Up to 30,000 people can be held in the centres at any period, with the EU expecting up to 120,000 migrants annually to pass through them.

Until migrants complete the vetting procedure, they will not be deemed to have entered the European Union.

- Solidarity mechanism -

The new system would reform the EU's so-called Dublin III mechanism under which, generally, the country in which an irregular migrant first steps foot is responsible for handling their case.

Currently that places stress on Italy, Greece and Malta, which have received the bulk of land and sea arrivals in recent years.

Under the new rules, an EU country which has given a university degree or diploma to an asylum-seeker would take over their dossier.

And a mandatory solidarity mechanism would force all member states take in a certain number of asylum-seekers arriving in the outer-rim countries.

If they choose not to, they could provide money or other material or personnel contributions to those that do. The level of contribution would be based on population, GDP, and the number of asylum applications the country receives.

At least 30,000 asylum-seekers a year will come under this relocation system, while countries would pay 20,000 euros ($22,000) for each asylum-seeker they decline to accept.

- Surge response -

The package establishes an emergency response in the event of unexpected migration surges -- the same sort of refugee crisis the EU faced in 2015-2016 when more than two million asylum-seekers entered the bloc, many of them from war-torn Syria and Afghanistan.

It would require member states to reduce protections for asylum-seekers, making it possible to hold them longer than usually permitted in detention centres on the EU's external borders.

EU members wants to address the "instrumentalisation" of migratory flows by outside countries. Belarus and Russia have been accused of encouraging migrants to cross their borders to destabilise the EU.

- 'Safe third country' -

The concept of a "safe third country" will be allowed when vetting asylum-seekers.

That could mean that an irregular migrant who came to the EU via a country deemed "safe" enough to lodge a request for protection could have their EU application rejected. But for that to be invoked, a "link" has to be established between the asylum-seeker and the transit country.