The British human rights lawyer, Ben Emmerson QC, is taking the case of ousted Catalan independence leader Carles Puigdemont to the United Nations, arguing that Spain has violated his right to participate in political life through a “repressive” legal crackdown.

Speaking in Brussels on Friday after Mr Puigdemont dropped his bid to return as president, Mr Emmerson accused the Spanish government of directing all the organs of state to “squeeze the life” out of the independence movement.

Mr Emmerson - who has represented high profile clients such as the wife of Alexander Litvinenko and former Guantanamo detainee Moazzam Begg and has already taken up the cases of three jailed Catalan separatists - said that the Spanish crackdown was a violation of international treaty obligations.

“Spain is holding a sword of Damocles over the head of the Catalan people, implementing a strategy that is designed to cower them into submission,” he said.