Britain takes great pride in its position as one of the few countries in Europe that has been governed continuously through a system of parliamentary democracy for centuries.

Any suggestion therefore that Britain does not abide by the principles of democracy and – worst of all – shows sign of dictatorship is bound to provoke an angry reaction.

So the president of the European Court of Human Rights found himself under fire tonight from Eurosceptics and pro-Europeans after suggesting that Britain will look like Greece under the rule of the colonels if it refuses to abide by the court's ruling on prisoners.

Jean-Paul Costa drew the parallel with the colonels' dictatorship of 1967-74 when he was asked by the BBC what would happen if Britain withdrew from the court or refused to abide by its ruling on prisoners. The comments by the Tunisian-born French president came a week after MPs voted overwhelmingly to uphold the blanket ban which prevents prisoners from voting. The court ruled last October that Britain had to lift the ban.

This is what Costa said when he was asked what would happen if Britain abandoned the European Convention on Human Rights or refused to abide by the European Court of Human Rights ruling on prisoners. Costa told Shirin Wheeler, the presenter of the BBC Parliament programme The Record Europe:

I would say that it would be a disaster. A disaster certainly for the Council of Europe and the court but also a disaster for the United Kingdom. I say it respectfully. The UK was one of the states founding the convention, one of the founding states of the Council. [The] UK has always been a supporter for the court and many times model for the legal systems of other countries. Many systems took advantage through the case law of our court of the legal traditions of Britain.

Wheeler asked why it would be a disaster for Britain. Costa said:

For the image of Britain I will say a simple things and again I hope this will not be considered as not respectful. The only country which denounced the convention actually was Greece in 1967 at the time of dictatorship of the Colonels. Of course after seven years, when democracy was restored in Greece, Greece returned to the Council of Europe and the convention. I cannot imagine – even if I can understand some irritation that [the] UK which is a great country I admire the UK – could be in the same situation as the Colonels in 1967.

Costa's remarks are of particular interest because he he was one of the judges on the ECHR who dissented against the decision on prisoners. He tells Wheeler he can understand the anger in Britain at the ruling:

I can understand of course. I would not say that I approve it but I can understand for two reasons. First of all because it seems a little paradoxical that people who have breached the criminal laws – sometime murderers or rapists or serious offenders – have to be entitled with the right to vote. And the other reason is that of course in some countries there is a feeling that it's not for a court like the court in Strasbourg to give instructions as regards for instance the right to vote which is certainly the core of democracy and which should be left to Parliaments.

The president goes on to say that the treatment of prisoners is a political matter:

There is a trend in Europe to increase the rights of prisoners in order for instance to facilitate their re-insertion in society after having finished the term of imprisonment. So as I said I can understand, I would not say I approve or disapprove as this would be a political judgement. There is another reason why the reactions in some countries are more important. When you deal with something like right to vote is that its not an absolute right. Prohibition of torture of course is obviously an absolute right, respect to life is practically an absolute right and you have some other rights protected by European convention which are absolute and you cannot derogate to them. When you arrive to the field of political rights even freedom of speech of course its more controversial and more nuanced.

Buy Costa says he has to abide by, and now uphold, the court decision after dissenting:

Of course the subjective feelings of the judges, of any individual judge are important. But what is also important, what is even more important, is really the collective deliberation of the court and finally the case law deriving from the majority. I myself, as you say, was a dissenter in this case. And my dissent is public, it's annexed to the judgement. But of course I have to assume now to be in conformity with the judgement of the majority. One of the reasons why I was dissenting at the time is that right to vote, even is the core of democracy, can receive some different interpretations from one country to the other.

That may offer some comfort to Eurosceptics who are pressing for Britain to abandon the ECHR. But they may not like Costa's staunch defence of the court and the European Convention on Human Rights. This is what he said when Wheeler asked him about an international court over-riding a national parliament:

Yes it's a very difficult question, but a very serious one. When the states decided to sign then ratify the convention they did accept that international law and international court created this in the convention were in some cases possibly above the national law. That's the reason why the convention was designed. And of course when the judgements of the court are in conformity or in the agreement with the decisions of the legislator or the court in a specific country nobody criticises because they say 'well there is a confirmation of what we did'. But from time to time there is a discrepancy or a divergence between our judgements and domestic law and domestic legislation and domestic case law so that's why there are sometimes critics or attacks against the court. Still I think the raison d'être of the court is to be a little above the national laws of course with prudence and self restraint.

Asked why that is necessary, he replied:

Well it's necessary for again two reasons. First of all for trying to harmonise legislation in Europe. I don't say unify, because each country has legal traditions, cultural traditions and so on but harmonising the trends of society and of the field of freedoms and liberties. And the other reason is that precisely the countries were not obliged to conceive to draft to sign and to ratify an international convention. So if they decided so in the 1950s it was precisely to create something which was supra-national. Well of course it was not absolutely obvious to do so even in 1950 but after all the disasters of the second world war the European states decided to do so. And the reason why they decided to do so is not obsolete it's still valid.

The criticism of Costa came swiftly tonight. This is what Sunder Katwala, the mild pro-European general secretary of the Fabian Society, tweeted: