European leaders are preparing for Britain to begin Brexit imminently, amid signs that Theresa May could activate Article 50 divorce proceedings as early as Tuesday.

During a summit of the remaining 27 EU members in Brussels on Friday, leaders were told to expect London to trigger exit talks next week and to prepare for a Brussels gathering on April 6 to respond to Britain's formal letter of notification.

One UK government official involved in the process said he "hoped" that Article 50 could begin on Tuesday when Mrs May is due to address the House of Commons, but would certainly start by the end of the week.

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Donald Tusk, the EU Council president, said that other European capitals would be ready to issue draft "guidelines" for negotiations within 48 hours. The EU is "well prepared for all procedures", he said, at the conclusion of a meeting at which Europe's political elite continued fleshing out plans for life without the UK in the bloc.

Aware that the long wait for Article 50 may soon be coming to an end, EU leaders also threw down some markers on how complex they expect the exit talks to be.

Charles Michel, Belgium's prime minister, said that "there will be difficult discussions on all subjects but also on the financial aspects" of Britain's departure. "The British did not make a good choice."

Mrs May faces votes in both houses of parliament on Monday which are likely to give her the authority to begin Brexit.

The prime minister will make a statement to parliament on this week's Brussels summit on Tuesday, a day later than usual, prompting speculation that she may use the moment to start the two-year negotiation period.

On Friday, Downing Street said only that she planned to do so "by the end of the month". Two senior EU figures involved in preparations said they doubted that Mrs May would wait for long to notify once she had secured parliamentary approval.

German chancellor Angela Merkel said that if the UK triggered next week, then the other EU-27 leaders could meet on April 6 to agree the guidelines for the exit talks.

The date was confirmed by Enda Kenny, Ireland's prime minister. Speaking to reporters, he said it would be possible to meet then if "the prime minister moves Article 50, I think, by the March 15", adding that Mrs May had not told him the exact date Brexit would be triggered.

Should Britain take until the end of March to notify, the EU plans to hold its own summit either in late April or early May.Jean-Claude Juncker, the EU commission president, struck a philosophical note after the Brussels meeting, saying that he hoped that Britain's decision could one day be reversed."

I don't like Brexit, because I would like to be in the same boat as the British," he said. "The day will come when the British will re-enter the boat, I hope."

In Monday's debate, Mrs May will try to kill two additions to the legislation that were approved by the House of Lords. The first seeks to unilaterally guarantee the rights of EU citizens currently living in the UK and the other seeks a meaningful vote on the final deal in parliament.

As many as 20 Conservative MPs will spend this weekend contemplating whether to rebel against Mrs May. Many are hoping that the prime minister will compromise. They are seeking a verbal assurance on parliament's future role from a senior minister — David Davis is the most popular choice among potential rebels — in exchange for their support in removing the Lords' amendments from the Bill.

But Downing Street said that Mrs May did not plan to speak to wavering MPs over the weekend and played down suggestions that she would offer them the reassurances they are looking for.

"Our position has not changed. What is important to us is that we have an unamended Bill," a Downing Street spokesman said. "The House passed the Bill unamended and we are clear that we want it to pass unamended again."

Although the House of Lords could theoretically reinstate amendments when the bill returns to the upper house, there was little sign that the lords would be able to muster enough opposition.

Additional reporting by Kate Allen, Paul McClean and Rochelle Toplensky