A Dutch judge has said he will ask the European Court of Justice to answer key questions about the rights of UK citizens on the continent post-Brexit, in a decision that could provide clarity for some one million Britons living in the EU.

Judge Floris Bakels said in a written ruling that "there has to be more clarity about the consequences of Brexit for EU citizenship", according to a statement by the court in Amsterdam.

A group of British citizens who live in the Netherlands had asked the court to refer their case to the European Court of Justice last month in a bid to protect their EU citizenship rights after the UK leaves the EU in March 2019.

Officials negotiating Britain's exit have made progress on the protection of rights of EU citizens living in Britain and UK citizens living on the continent, but no full agreement has yet been reached on the issue.

According to the Treaty on the Functioning of the EU, any person who is a citizen of an EU nation is automatically also an EU citizen. EU citizenship grants rights including the ability to move, work and live freely within the bloc.

Christiaan Alberdingk Thijm, the Dutch lawyer who represented the Britons in the Amsterdam court, welcomed the ruling.

He said: "Theresa May famously said 'Brexit means Brexit', but the Brits currently living on the continent have no idea what that means for them.

"Are you an EU citizen for life, or can your citizenship be taken away from you? That is the fundamental question that will be put forward to the European Court."

One of the Britons who filed the case, Stephen Huyton, who has lived in the Netherlands for 24 years, said he was delighted with the decision.

"However, this is but the first step to clarity about what Brexit means for our EU citizenship," he said in a statement. "This case has always been about seeking clarification."

It was not immediately clear when the European Court of Justice would deliver answers to the questions.