LONDON (AFP) - British Prime Minister Boris Johnson started phoning EU leaders on Saturday (Oct 5) to sell his proposals for a managed Brexit, but met with pressure to revise his offer - and do so quickly.

Finnish counterpart Antti Rinne - whose country currently holds the rotating presidency of the European Union - said he told Johnson "it is important to find a solution within a week".

"Johnson said he agreed with the timetable," Rinne added.

The British leader was expected to call the leaders of other EU countries in the wake of his proposals being given short shrift by Brussels after they were submitted on Wednesday.

As they stand, "the UK proposals do not provide a basis for concluding an agreement," a European Commission spokeswoman said on Friday.

Hours-long talks on Friday between a top British Brexit official and the EU team headed by top negotiator Michel Barnier ended without progress.

They were to resume Monday, despite Britain having been keen for them to continue through the weekend.

Johnson calls his plan "a fair and reasonable compromise" but also a broad "landing zone", which suggests he might yet budge on issues that the EU finds unacceptable.

Time is running short for the two sides to close the gap.

Johnson is determined to take Britain out of the European Union at the end of this month come what may.

An Oct 17-18 EU summit is to determine whether the country is headed for a Brexit deal, no-deal, or an extension.

A week's window

European diplomats have echoed Ritte's warning that London needs to offer revised, viable proposals before the end of next week, so any haggling and legalistic work is done before the summit.

The EU refuses to characterise the talks held so far as negotiations, underlining a preference to stick with a Brexit withdrawal agreement that was struck with Johnson's predecessor Theresa May but rejected three times by British MPs.

The main sticking point is a "backstop" for Northern Ireland.

It would see all the UK, or at least Northern Ireland, remaining in the EU's customs union.

That is meant to guarantee no border springs up between the British territory and EU member Ireland - which would threaten the hard-won Good Friday peace accord - while also maintaining the integrity of the EU's single market.

Britain's current idea for an alternative is for untried technology to remove the need for most but not all border checks, and for EU standards on goods to continue to apply in Northern Ireland to facilitate trade.

This border plan is not acceptable for the EU. It sees the potential for rampant smuggling, especially as Johnson intends for the rest of the UK to diverge from EU labour, environmental and tax norms to aim for a regulation-lite economy on Europe's doorstep.

"I made clear that the proposed solutions do not ensure the respect of the Good Friday Agreement, EU unity or the integrity of the single market," Ritte said.

Early UK elections possible

Nor does the EU agree with a proposal that Northern Ireland's assembly be given a right to effectively veto the post-Brexit customs arrangement.

If those two proposals are red lines for Johnson, it is hard to see the EU moving talks into the negotiation phase.

Yet if he bends on them, Johnson risks losing tenuous support in the British parliament to maybe pass a Brexit deal, reliant on 10 Democratic Unionist MPs from Northern Ireland and hard-core Brexit MPs in his Conservative Party.

If thwarted, Johnson's best bet may lie with early elections - but those could only happen after the date he has said Brexit would happen.

There he also faces a challenge, with the British parliament having passed a law requiring him to seek a Brexit extension from the EU by Oct 19 if he has not reached a deal by then.

British media speculated that Johnson might seek to sabotage any extension request he is forced to make against his will.

One path included his ministers asking an EU member state to block the unanimous approval needed for an extension, with Hungary cited as a likely ally to break EU ranks.

But Budapest denied Britain had approached it with such a request, and a Hungarian foreign ministry source told AFP: "To date there is no request for a delay, hence there is no point in speculating about anything."