French President Emmanuel Macron has outlined his vision for a "profound transformation" of the European Union, unveiling a series of proposals to deepen the bloc politically and harmonise rules across the continent.

Macron used the speech at Sorbonne University in Paris on Tuesday to argue the case for institutional changes, initiatives to promote the EU, and new ventures in the technology, defence and energy sectors.

"The Europe that we know is too weak, too slow, too inefficient," he said on Tuesday as he began the closely watched address.

"But Europe alone can give us the ability to act in the world faced with big contemporary challenges."

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Macron's proposals for a post-Brexit shake-up include a Europe-wide "rapid reaction force" to work with national armies, and plans to give the 19-member eurozone a finance minister, budget and parliament.

He also called for a new tax on technology giants such as Facebook and Apple - accused of paying too little corporate tax on their businesses in Europe - and an EU-wide asylum agency to deal with the refugee crisis.

He even raised the prospect of major changes to the Common Agricultural Policy, the EU's giant farm subsidy programme, which has historically been defended by France and its powerful agricultural lobbies.

Shock election results

Macron had been seeking German Chancellor Angela Merkel's endorsement of his reform agenda.

However, his plans were dealt a blow by shock election results that saw the anti-immigration, eurosceptic Alternative for Germany (AfD) emerge as the country's third-largest party.

Merkel must now try to form a government that is likely to include the Free Democratic Party (FDP), whose leader is an outspoken critic of Macron's European agenda and has said a eurozone budget would be a "red line".

Macron appeared to respond to Christian Lindner, the FDP chief, directly on Tuesday, saying: "I don't have red lines, I only have horizons."

Cooperation from Germany - the other half of the so-called Franco-German motor at the heart of the bloc - is essential, though Macron will also need to convince other European partners.

Along with Brexit and the German elections, Macron's proposals are likely to top the agenda at a two-day summit of all 28 EU members in Estonia starting on Thursday.

Following Tuesday's speech, Juncker, head of the European Commission, the EU's executive arm, praised Macron, saying the bloc required "courage" to move ahead.

"A very European speech by my friend Emmanuel Macron. Europe needs courage. Thank you for your support for the work of the EU institutions," Juncker said on Twitter.

"What we need now is a roadmap to advance the Union at 27. We have to openly discuss all ideas and decide before May 2019."

Britain will leave the EU in March 2019, and European Parliament elections are due the following May or June.

Juncker has also called for a summit in the Romanian town of Sibiu the day after Brexit to draw up a plan for the way forward.