Jean-Claude Juncker was engulfed in a cronyism storm yesterday after parachuting his chief of staff into a job as the EU’s top eurocrat.

The European Commission president faced calls to sack notorious German official Martin Selmayr – nicknamed The Monster – after critics described his promotion as a ‘cloak and dagger’ coup. Leading MEPs threatened to topple his Commission, claiming the dramatic rise of the unelected lawyer had destroyed the credibility of Brussels.

The European Ombudsman, an independent EU body that looks into wrongdoing, was yesterday considering an investigation alongside a separate probe by the European Parliament.

Jean-Claude Juncker was engulfed in a cronyism storm yesterday after parachuting his chief of staff into a job as the EU’s top eurocrat

The uproar was triggered after Mr Selmayr, 47, was chosen to lead 33,000 officials as the EC’s secretary-general in a fast-tracked application process featuring no other candidates.

Mr Selmayr, a member of Angela Merkel’s Christian Democratic Union, will oversee the EU’s Brexit contingency planning despite recently being pinned as the source of damaging leaks against Theresa May.

He has developed a reputation for hostility towards Britain, borne from his belief in greater European integration and traditional UK opposition to such moves.

As Mr Juncker’s chief enforcer, the former press officer has gained notoriety among EU governments for his bullish management techniques. Commissioners have described his controlling style as ‘poisonous’. Critics have suggested that the unorthodox ‘power grab’ to cement the new job was orchestrated to ensure that EU member states did not have enough time to intervene, with Mr Juncker due to step down in 2019.

Reports have claimed Mr Selmayr eased his way into the job by promising to boost the ‘golden goodbye’ perks offered to the EU commissioners who rubber stamped the move when they retire

Following his rapid appointment, Mr Juncker said: ‘He [Mr Selmayr] has one thing in common with me – we both have enemies.’ MEPs used an emergency debate on the issue in Strasbourg yesterday to call for urgent action while likening Mr Juncker’s leadership to China’s ruling Communist Party.

They said that allegations of rule-breaking had turned the EU into a laughing stock that would prove more damaging than the existence of Eurosceptic parties.

Guy Verhofstadt, the senior MEP who heads the European Parliament’s Brexit team, yesterday described the promotion as a ‘misstep’ that is ‘damaging for Europe as a whole’.

MEPs accused Mr Juncker of shirking responsibility by refusing to attend the debate, but the EC has said rules were followed ‘religiously’. Nigel Farage, the Ukip MEP, said yesterday: ‘Selmayr’s appointment is like a palace coup under cover of bureaucratic darkness. It smacks of nepotism, unaccountable government, abuse of public funds.’

Reports have claimed Mr Selmayr eased his way into the job by promising to boost the ‘golden goodbye’ perks offered to the EU commissioners who rubber stamped the move when they retire.

Guy Verhofstadt, the senior MEP who heads the European Parliament’s Brexit team, yesterday described the promotion as a ‘misstep’ that is ‘damaging for Europe as a whole’

This allegedly included a promise to extend the number of years they could receive ‘transition’ payments worth up to two-thirds of their salary, as well as the use of a chauffeur and EU office.

The EC has described the claims as ‘nonsense’ and pointed out that it cannot solely offer the extension of such benefits.

Mr Selmayr will not immediately receive a boost to his salary, which currently sits at up to £195,000, although he will be in line for potential boost of £17,000 in the near future. Amongst a spate of controversies attached to his name are claims Mr Selmayr leaked details about a dinner between Mr Juncker and the Prime Minister in Downing Street last October.

He later denied the claims, suggesting claims of his involvement were an attempt to ‘frame [the] EU side and to undermine’.

The EU’s budget and human resources commissioner Gunther Oettinger pleaded with MEPs yesterday not to ‘discriminate’ against civil servants such as Mr Selmayr. He said: ‘We shouldn’t turn Mr Selmayr into some kind of monster. He’s not a monster. Please give him a chance.’

An EC spokesman said: ‘Everything was done strictly by the book.’