Dissenting EU states may end up in court or face as-of-yet undefined sanctions if they refuse to let the European Commission dispatch guards to their national borders.

The threat is part of a bill on a European border and coast guard system unveiled on Tuesday (15 December) by the Brussels-executive, which says EU guards can be deployed on the bloc’s external frontiers without the consent of the host state if need be.

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EU vice-president Frans Timmermans and EU migration commissioner Dimitris Avramopoulos said the proposal would not strip member states of sovereign rights.

They also said it’s needed to defend the passport-free Schengen zone.

“If we want the Schengen system to continue to perform, to do better than it did before, we need to have more capacity to analyse what is actually happening, to do this quicker, and on the basis of this analysis be able to react to potential threats or changes in the situation,” said Timmermans.

The new system would replace the smaller EU border agency, Frontex, with a so-called European Border and Coast Guard Agency.

The new agency would have a reserve pool of 1,500 border guards, which can be dispatched in a matter of days to an external border to prevent a crisis from escalating.

The plan is part of a broader effort to regain control over the EU's external border following huge arrivals of asylum seekers.

EU officials and leaders say the Schengen area is at risk of collapse if external borders are not properly managed.

All eyes are on Greece, which, over the past 11 months, has received the bulk of irregular migrants.

Most come from Turkey to Greek islands in the Aegean before heading through the Western Balkans to mainland EU states.

The past two weeks alone saw 45,255 migrants and refugees reach Greek islands from Turkey, according to the International Organisation for Migration.

It says almost 80 percent crossed into Macedonia in the same period.

Last Friday, Greek prime minister Alexis Tspiras voiced support for the new border guard plan, but said Athens would remain the ultimate decision maker on border control.

Commission officials say the hosting member state would take the operational lead, but outstanding issues remain should the EU state flat out refuse.

The commission may adopt a so-called implementing decision to request direct intervention of the Agency if the member state either fails to control its border or refuses to host the EU guards.

The secondary legislation requires a positive opinion, based on a qualified majority, from a committee composed of experts from the 28 EU states.

“If there is no qualified majority then the commission cannot implement the decision,” noted an EU official.

The official added that “it is the loyal duty of the member state concerned to implement decisions taken.”

Timmermans, for his part, described it as a “safety net, as the ultimate measure that might be possible theoretically.”

The decision would be based on a “vulnerability” risk assessment conducted by an agency liaison officer sent to the border area.

Asked what sanctions and infringements await dissenting member states, an EU official said details are yet to be clarified.

“The member state would be infringing its obligation,” said the official.

The move follows other EU plans which later fell foul of member states, who failed to provide the extra manpower needed to get so-called hotspots, where migrants are identified and registered, up and running in Greece and Italy.

Frontex had asked member states to supply 743 guest officers to work at the external border in Greece but only received 447.

A two-year relocation scheme to dispatch 160,000 arrivals in Greece and Italy to other member states has also stalled. Only 64 asylum seekers have been relocated from Greece and 144 from Italy so far this year.

The new border bill still needs to go through normal legislative procedures at the European Parliament and the Council, representing member states.