European Court of Justice has 28 judges, one from each member nation

The Supreme Court could decide to refer the whole matter to Luxembourg

High Court said Parliament had to have its say before Article 50 enacted

Eleanor Sharpston QC (pictured) has been Britain's judge on the European Court of Justice since 2006

A top judge has stoked the increasingly bitter row over Brexit by warning that the European Court of Justice will have the final say over the process.

In comments that will cause fury, Advocate General Eleanor Sharpston QC said the Luxembourg court was in charge of the 'rules of the club' and would be responsible for settling any disputes.

Tensions are reaching fever pitch amid a series of legal challenges to Theresa May's powers to trigger Brexit.

The government suffered an humiliating defeat in the High Court earlier this month, when it decided Parliament has to approve invoking Article 50 - the formal two-year mechanism for leaving the Brussels club.

The Supreme Court is due to consider an appeal next week in what could be a pivotal moment in the Brexit process.

A separate legal challenge is being threatened over whether leaving the EU automatically means quitting the single market - potentially requiring a distinct approval by parliament.

Ms Sharpston, who is the British judge on the ECJ, raised the prospect that the key decisions over how Article 50 proceeds will be taken by that court.

'If you join the club and you wish to leave the club, you leave in accordance with the rules when you join the club…the rules of this club are the ones contained in Article 50, and the interpretation of those rules is a matter for this Court (the ECJ),' she told Sky News.

Ms Sharpston told Sky News the ECJ would not interfere with the Supreme Court appeal and was 'fully aware of the sensitivity and delicacy and constitutional importance of the issue'.

The Supreme Court does have the power to refer the decision to the ECJ, which sits in Luxembourg.

The ECJ has 28 judges, one from each EU country.

EU council president Donald Tusk, pictured with Mrs May in Downing Street in September, angered British MPs by blaming UK voters for 'creating uncertainty' by opting for Brexit

Asked how quickly the ECJ could give a ruling if it was required, Ms Sharpston, 61, said: 'If you look at what has happened in the past when we've had an accelerated procedure, the answer is probably given within four to eight months.'

Earlier EU president Donald Tusk blamed the millions of Britons who voted for Brexit for creating uncertainty and dismissed calls from UK MPs for a quick deal over British expats in Europe as 'nothing to do with reality'.

Prime Minister Theresa May has said she is eager to confirm EU nationals living and working in Britain can stay after Brexit but has insisted there must be a matching deal for Britons abroad.

Mrs May proposed a deal that could have been completed by the EU summit in two weeks' time but German Chancellor Angela Merkel refused.

Last night Mr Tusk, the EU Council president, heightened tensions as he dismissed a call from more than 80 MPs to facilitate talks on a reciprocal deal for foreign workers in order to reassure them of their rights to stay after Brexit - insisting June's Leave vote is the only cause of uncertainty.

(Left to right) Chuka Umunna, Nick Clegg and Anna Soubry have formed a cross-party pressure group, Open Britain, in a bid to influence the Brexit negotiations

The future of Poles in Britain was discussed at No 10 yesterday as Polish Prime Minister Beata Szydlo visited Downing Street for talks with Mrs May

He said it would amount to starting talks on Brexit and insisted this can only be done by Britain triggering Article 50 of the EU treaties.

Labour leader Jeremy Corbyn has said that if the vote were to go before Parliament he would not seek to overturn the Brexit decision.