The plan is aimed at boosting security on Europe's perimeter while preserving the 26-nation Schengen zone at the continent's heart, within which people can travel freely across national borders without passport checks.
If approved by governments, a new European Border and Coast Guard will replace the EU's Frontex agency and have expanded powers, including the new standby force. It will have funding worth 322 million euros ($354 million) by 2020.
Officials presented the scheme as a boost for states on Europe's Mediterranean frontier. Obligations to rescue and shelter those desperate enough to take to the sea have seen Greek and Italian coastguards and immigration services swamped by a million people this year, many fleeing civil war in Syria.
The executive European Commission also wants the power to deploy EU forces without the consent of the member state concerned -- an idea that has already hit resistance in national capitals and which many see as impractical.
However, frustration among northern powers, including France and Germany, at failures by Greece and Italy to document and screen masses of people arriving by boat from Turkey and Africa has driven demands for more centralized European control of the Schengen zone's external frontiers.
"In an area of free movement without internal borders, managing Europe’s external borders must be a shared responsibility," said Commission deputy head Frans Timmermans.
Concern that the Islamic State attack on Paris last month was carried out in part by militants who had traveled along the migration route from Syria via Turkey and Greece has also increased pressure for tighter checks on the frontiers.
The Commission proposal says the EU agency overseeing the frontiers should be able to "intervene immediately in crisis situations" and deploy border guards from the standby pool, drawn from other national border guard forces, within days.
“States may not agree. Nevertheless, it is the decision taken. It is the loyal duty of the member state concerned to implement decisions taken,” said an EU official.
However, EU officials stressed that national governments would be able to block that if a majority of them were against.
"There is a lot of debate about us imposing our will on member states," Timmermans told reporters. "This is a safety net. Most member states would gladly accept the help."
Migration Commissioner Dimitris Avramopoulos told the European Parliament in Strasbourg: "What we are creating today is more Europe." He said the proposal would "allow us to move ahead more united, more decided, more resolved".
But the plan must still overcome concerns within the 28-nation EU. "The proposal means bringing in through the back door infringements on our sovereignty," said Notis Marias, a lawmaker from Greece. "We won't go for this at all."
Others argued failure to strengthen external borders would spell the end of Schengen, seen by many as one of the EU's most cherished achievements.
"If the external borders aren't secure, the internal borders will be raised again," said Esteban Gonzalez Pons, a Spanish conservative. "If we have common problems, we must have common answers."
The current staffing of Frontex, which serves to coordinate national border agencies, is around 400. That will more than double to 1,000 by 2020. In addition, member states will have to put a total of at least 1,500 personnel on standby for deployment within days.
The agency will also have a Returns Office with the task of stepping up expulsions of those who fail to qualify for asylum -- potentially hundreds of thousands of people, though many question how practical it is to detain and deport large numbers.
EU proposals may briefly discuss the plans at a two-day summit starting in Brussels on Thursday. The migration crisis has drive a wedge among member states that many fear threatens the overall unity of the 28-nation bloc.
The Commission also proposed legislation to increase systematic security and identity checks at the Schengen frontiers, including of EU citizens who typically pass with limited scrutiny at present.
Many of those who have carried out Islamist attacks in Europe in the past two years have been EU citizens, notably French and Belgians, who have fought in Syria and gone home.
FACTBOX: EU plan for new border guard to curb migrant influx
he European Union's executive arm presented a plan on Tuesday to strengthen its external borders as it struggles with its worst migration crisis since World War Two.
Below are the main points of the proposal from the European Commission.
* European Border and Coast Guard
- A new agency established to enhance control of external borders, with the right to intervene even without request from a member state and to operate on the territory of third countries.
- Budget proposed at up to 238 million euros ($261 million) in 2016, 281 million euros in 2017 and reaching 322 million in 2020. Staffing to double from some 400 at EU's border agency currently to 1,000 by 2020.
- The Commission would have the right to order deployment of the European Border and Coast Guard forces in a country, even without it requesting it, if controls at the external border are deemed insufficient to an extent that puts at risk the whole of the EU's frontier-free Schengen zone.
The Commission would take any such decision in consultation with a committee bringing together officials from member states where a qualified majority would be required, meaning 16 out of 28 countries representing at least 65 percent of the total EU population must be in favour.
- Member states to dedicate at least 1,500 border guards to the agency and be ready to deploy them within three days.
- The new agency would be more involved in search and rescue operations, manage joint operations and rapid border interventions if requested by a member state.
- The agency would play a bigger role in expelling third country nationals staying in the EU illegally and would issue a standarised EU-wide document for the return trip.
* Systemic checks for all travellers at external borders
- EU citizens will undergo mandatory systemic checks on entering or exiting the Schengen zone. Currently only third country nationals undergo systemic checks. More checks will also be required against existing databases.