Paris (AFP) - French President Emmanuel Macron pleaded Tuesday for a new era of European integration, calling on his EU partners -- particularly Germany -- to raise their ambitions and go further in linking their economies, governments and armies.

The 39-year-old leader spoke for more than an hour and half in front of students at the Sorbonne university in Paris in a passionate speech that contained a raft of proposals for the 28-member European Union.

"The Europe that we know is too weak, too slow, too inefficient," he said. "But Europe alone can give us the ability to act in the world faced with big contemporary challenges."

Macron's proposals for a post-Brexit shake-up included a finance minister, budget and parliament for the 19-member eurozone, as well as a European "rapid reaction force" to work with national armies.

Macron is desperate for German Chancellor Angela Merkel's endorsement of his reform agenda, but his plans were dealt a blow by Sunday's election in Germany that saw eurosceptic parties make gains.

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

- 'Only horizons' -

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

But he also steered clear of defining how big any future eurozone budget might be, having previously said he wanted it to be the equivalent of "several points" of eurozone GDP which could amount to several hundred billion euros.

Among his propositions was a new type of tax on technology giants like Facebook and Apple -- based on how much value they create in a country rather than their profits -- and taxes on financial transactions across the bloc.

An EU-wide agency to handle asylum requests, a beefed up common border force and a European innovation agency were among other ideas for EU organisations that would require further pooling of national sovereignty.

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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.

- Opposition inevitable -

Macron's vision for a new phase of European integration, a process which started in the post-war era and led to the creation of the EU, is likely to run into objections in some countries.

Nationalist governments in Poland or Hungary do not share his desire to send new powers to Brussels, while his plan for harmonised corporation tax will ring alarm bells in low-tax countries such as Ireland.

Addressing the issue of Britain's planned departure from the European Union -- the most vivid illustration of growing nationalist feeling in the bloc -- Macron appeared to leave the door open for London to rejoin or change its mind.

"In a few years, if they want, the United Kingdom could find its place... In this reformed and simplified EU that I'm proposing, I can't imagine that the United Kingdom could not find its place," he said.

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 from Thursday.

European Commission chief Jean-Claude Juncker welcomed the speech, saying the bloc required "courage" to move ahead.

Macron's style is also likely to be widely discussed by his European partners and his pitch for the leadership role for the continent has grated with some policymakers in Germany since his election in May.

One person close to German Chancellor Angela Merkel accused him of acting like a "Sun King" with a "God-given right to rule" in recent comments to AFP on condition of anonymity.

But the former investment banker was undeterred Tuesday, saying European leaders needed to revitalise the project to take the sting out of rising right-wing nationalism on the continent.

"We don't have a choice," he said.

He made frequent references to the European wars of the 20th century just days after the right-wing populist party Alternative for Germany (AFD) shocked Europe by winning 93 seats in parliament.

"Europe enabled us to turn our backs on the wars. We need to find this ambition again," he said.

French officials considered that now was the best time for Macron to lay out his vision for Europe as Merkel begins cobbling together a coalition which will agree a detailed roadmap for the four-year term ahead.

"It's an opportunity we can't afford to miss," a French presidency official told a briefing on Monday.