EU cannot oblige UK to trigger exit procedure

But British politicians are dragging their feet, prompting fears of a political stand-off between the EU and the UK.

There are no clear rules what format that notification should take, but EU officials said it should unambiguously express the intention to leave.

The notification triggers a two-year negotiating period after which the other member states could decide to extend that period. There is no legal maximum time-frame for the talks to close.

EU insitution leaders urged London on Friday to "give effect to this decision of the British people as soon as possible, however painful that process may be."

The Slovak foreign minister, whose country will take over the rotating presidency of the EU in July also weighed in.

"The biggest issue to be discussed now is when the process of actual British disconnection from the EU will start. The overwhelming feeling among member states is that we simply cannot afford to wait until the Conservative party find a new leader, because our citizens and the British voters have the right to know the consequence of their vote,” Miroslav Lajcak told journalists in Luxembourg.

"I simply cannot imagine the situation where we will tell [the people] that we have to wait until the Conservative party gets its act together,” he added, but when asked how member states can pressure UK to start the process, he said: “We can talk."

However, prime minister David Cameron, who said he would resign after the summer, said there is no need for a precise timetable.

Boris Johnson, the Conservative MP who led the Leave campaign and is a possible candidate for the premiership, said on Friday there is “no need for haste”.

"Nothing will change over the short term” he said, adding that the country should not immediately trigger Article 50.

Leaders of political groups in the European Parliament have already criticised Cameron for delaying invoking Article 50, saying it goes against the will of the British voters.

Liberal group leader Guy Verhofstadt suggested the official notification from the UK could come as late as the end of 2016 or early 2017.

Only political pressure

But there is nothing the EU could do, other than exerting political pressure, as triggering an exit is the monopoly of the member state wishing to leave.

The longer the delay, the more uncertainty

"The referendum in itself does not count as a notification," Steve Peers, professor of EU and human rights law at the University of Essex, told this website, while some officials and MPs in Brussels said that the result itself could be interpreted as a legal trigger.

Peers said the logic behind the delay could be to give more time to the UK and the new government to work out a negotiating position. "The Leave side never thought about their negotiating position," he said.

He added that informally, the EU and the UK could nevertheless start discussions, but it could take several more months before the official notification is made.

The longer the delay, the more uncertainty it would create, and "more damage to the UK," Peers added.

Pieter Cleppe, from the British think tank Open Europe, told this website there is no way of legally kicking a country out of the EU.

He said the pressure to go ahead with triggering the official exit talks will eventually have to come from the Brexit camp.

'A very binding poll'

"If the Brexit vote is not followed by a move to leave, it could create a lot of discontent," Cleppe said, adding the delay means the UK government wants to buy time to create a framework for the talks, and prepare for the negotiations.

But Cleppe does not think a few months of delay would lead to a stand-off between the EU and UK. "Politically it is a very binding poll," Cleppe said.

"It will not be possible to get away with it," he added.

Once the official notification is passed on, the council will give a negotiating mandate to the EU commission, which should hammer out an agreement with the UK.

The final deal would need to be agreed by a qualified majority of the 27 EU countries, but would most likely require unanimity because of the sensitivity of the issues. The final withdrawal agreement also needs the consent of the European Parliament.