The UK’s post-Brexit trade deal with the EU could be referred to the European Court of Justice (ECJ), its president has revealed.

Koen Lenaerts said that while it was impossible to predict which aspects of any future UK-EU deal might be referred to the ECJ, it was highly likely it would “end up on the docket of the Court.”

His comments, however speculative, expose the very real possibility that Britain’s exit from the EU could be shaped under the jurisdiction it is determined to escape.

“It probably will, one day or another, end up on the docket of the Court – not because of the Court, but because of parties bringing the case,” he said.

However, the 62-year-old chief justice said judges would never offer advice or take political sides during any case and that while they cannot decline a case, they can only rule on legal arguments, not politics.

He also emphasised the ECJ’s independence from Brussels, based in “splendid isolation” in Luxembourg.

The prospect of court battles going on well after Brexit underlines the uncertainty surrounding the process.

However, he rejected suggestions by some legal analysts that the ECJ played an activist role in strengthening federal powers for Brussels or delivered rulings to quell rising euroscepticism.

“We are not pro-Union, we are not against Union,” he said. “We are pro law. The law is made by the political process.”

The UK Government will publish its White Paper spelling out its plan for Brexit after MPs have voted on triggering Article 50.

The Prime Minister said the detailed document would be published on Thursday.