As British Prime Minister Theresa May asks for Brexit to be postponed beyond midnight on Friday, the EU's ministers seek a credible plan to justify the delay.

(FILES) In this file photo taken on December 11, 2018 German Chancellor Angela Merkel (L) greets British Prime Minister Theresa May at the Chancellery in Berlin.
(FILES) In this file photo taken on December 11, 2018 German Chancellor Angela Merkel (L) greets British Prime Minister Theresa May at the Chancellery in Berlin. (AFP)

EU ministers warned Tuesday that Britain must come to this week's emergency summit with a credible plan to justify postponing Brexit, as last-ditch talks got underway across European capitals.

Britain's Prime Minister Theresa May was to meet her German counterpart Angela Merkel in Berlin and France's President Emmanuel Macron in Paris later in the day, before Wednesday's EU summit in Brussels.

She will ask for Britain's exit from the union to be postponed beyond midnight on Friday, to avoid a chaotic and disorderly divorce, and the other 27 EU leaders are expected to agree -- under conditions.

"We are in a very, very frustrating situation here," said Germany's minister for European affairs Michael Roth, as he and fellow EU officials arrived for Luxembourg talks on the eve of the summit.

Roth said that EU leaders would consider May's planned request for Brexit to be pushed back to June 30, but also perhaps for a "longer one, but this must also be subject to very strict criteria."

Scenarios on long delay 

Meanwhile, British MPs on Monday passed a new law aimed at preventing a no-deal Brexit this week by obliging the government to ask EU leaders for a delay.

Roth's French counterpart Amelie de Montchalin said EU capitals were digesting news from London late Monday that parliament had passed a law insisting that May seek an extension to avoid a "no deal" Brexit on Friday.

"We want to understand what the UK needs this extension for, and what are the political surroundings around Theresa May to have this extension," she told reporters.

"And then comes the question of the conditions of what role we'd want the UK to play during this extension time," she said.

France and other capitals are worried that if Britain accepts a long delay, and even elects a new batch of MEPs, its representative could disrupt EU budget planning and reforms during indefinite Brexit talks.

Ireland, which has much to lose if its larger neighbour quits the block without a deal, has been most supportive of an extension, but Foreign Minister Simon Coveney, also insisted on the need for conditions.

"No deal in my view would be an an extraordinary failure of politics and we need to ensure that that doesn't happen," he said.

"But of course there needs to be a real plan to go with a request for an extension -- that's credible -- in order for that extension to be agreed over the next three days, and I think that's likely to happen."

British MPs pass law to block no-deal Brexit

The law has been rushed through both chambers of parliament over the past week and was opposed by the government, which has said it could limit its room for negotiation with the European Union.

"This is a huge dog's dinner," Andrea Leadsom, who represents the government in parliament, told MPs.

"I fundamentally object to it on the grounds that it is totally unconventional," she said.

The law was passed on the initiative of MPs, subverting the normal order in which parliament debates and passes government-proposed legislation.

As a result of the law, the government now must put forward a motion in parliament on Tuesday setting out the delay that it will request at an EU summit on Wednesday.

MPs will be allowed to vote on this and make their own suggestions as to the length of the delay.

It allows the government to seek any extension from May 22 onwards. May has asked for a delay until June 30, but ultimately this is up to EU leaders and it could be longer.

The law does not actually prevent a no-deal Brexit when the deadline for Britain runs out on Friday, as that is the legal default if Britain and the EU cannot agree on an extension at the summit.

Britain could also choose to stop the entire Brexit process by revoking Article 50, the formal procedure for member states that want to leave.

The EU had previously agreed a short extension to the original deadline of March 29.

Source: TRTWorld and agencies