Human rights row: UK quitting would be disaster - ECHR head
The president of the European Court of Human Rights (ECHR) has warned that it would be a "political disaster" for the UK to quit the human rights convention.
Prime Minister David Cameron should "be very careful not to risk [Britain's] credibility", Dean Spielmann argued.
UK Justice Secretary Chris Grayling has spoken openly of the possibility of defying an ECHR ruling on prisoners' right to vote.
This would be a "violation of international law", the judge said.
But he declined to comment on the "political question" of whether the UK would be thrown out of the Council of Europe - the international institution that oversees the European Convention on Human Rights - if it did defy the prisoner votes ruling.
The UK has been on a collision course with Strasbourg since 2005, when the ECHR ruled that a ban on all prisoners voting was a breach of human rights, following a challenge by convicted killer John Hirst.
In February last year, MPs voted by 234 to 22 to keep the blanket ban, in response to a government proposal to give the vote to offenders handed a custodial sentence of less than four years.
Mr Grayling has told MPs they ultimately have the power to maintain the current ban, but there would be a "political cost" in doing so.
In an interview for the BBC's HARDtalk programme, Judge Spielmann said: "It is of course a problem if a country with a long-standing tradition of protecting human rights - and I would like also to pay tribute to the work which is done by the UK in the rest of the world promoting human rights - that this country would not comply with the rule of law.
"If Britain would leave the European Convention it would be a political disaster," he said. "For everyone who is dedicated to the effective protection of human rights, not only in Europe but also in the rest of the world because we have a unique system of protecting human rights.
"A very powerful system - admittedly that's true, but it has worked so well over the years, it has given Europe so much, and also the UK."
Mr Cameron has vowed that inmates will not be given the right to vote under his government, saying the idea makes him feel "physically sick".