EU countries can unilaterally end the divorce process from the bloc, the legal advisor to its top court said Tuesday in a closely watched case launched by anti-Brexit politicians in Britain.

The case was referred to the European Court of Justice by a Scottish court and hinges on whether the British parliament could simply revoke the country's ‘Article 50’ EU withdrawal process.

‘Advocate General Campos Sanchez-Bordona proposes that the European Court of Justice should declare that Article 50 authorises the unilateral revocation of the notification of the intention to withdraw from the Union,’ a statement from the court said.

‘That possibility continues to exist until the withdrawal agreement is formally concluded,’ the court added.

Judges at the ECJ usually, but not always, follow the legal opinions of the court's advocate general.

A British government spokesman said the advice would change nothing for Prime Minister Theresa May's government.

‘This is not a final judgment,’ he said. ‘It does nothing, in any event, to change the clear position of the government that Article 50 is not going to be revoked.’

‘It is an opinion offered by the advocate general, at this stage, no more than that,’ he added.

To be valid, any British revocation must be ‘decided in accordance with the constitutional rules’ of the member state and be the subject of a ‘formal communication’ to European Union leaders, the court said.

- 'Smooth and orderly' Brexit -

May's government argues it has no intention of halting Brexit anyway and that the case has been brought as a political tactic by pro-European opponents.

May is trying to sell an agreement on a ‘smooth and orderly’ Brexit to a hostile House of Commons, arguing that their choice is to back a deal or face the economic calamity of crashing out of Europe without a plan.

But pro-Europeans hope that if the European court confirms that Britain has the right to stop the countdown then a third option would emerge: stopping Brexit altogether and remaining in the EU.

The European Union institutions also oppose the Scottish case, fearing member states will tempted to launch their own speculative exit bids to extract concessions from Brussels -- only to reverse course.

Under Article 50 of the EU's Lisbon treaty, any member state can declare its intention to quit the union, a decision which for Britain comes into effect on March 29 next year.

Britain invoked the article on March 29, 2017 after voters backed Brexit in a national referendum the year before.

The country is on course to formally leave EU institutions in less than five months.

The decision remains hugely controversial, however, and a group of politicians -- members of the Scottish, UK and EU parliaments -- has brought a case arguing that Britain should have the right change its mind.

A court source told AFP that the decision could well be made before the end of the year, but the judges must first decide if the ECJ even accepts jurisdiction in the case.