World Bulletin / News Desk

The European Commission on Sunday insisted the controversial promotion of President Jean-Claude Juncker's top aide and enforcer was "in full compliance" with rules despite a growing cronyism row.

The scandal has gained momentum in recent weeks with the European Parliament launching an investigation and warning the affair risks fuelling eurosceptics around the continent.

But the commission insisted Selmayr's appointment was above board and made with the full backing of all EU commissioners.

"The decision was taken by the college of commissioners unanimously, in full compliance with the staff regulations and the rules of procedure of the commission," the commission said in a written response to a list of 134 questions posed by MEPs.

The row centres on what critics say was effectively an instantaneous double promotion for the 47-year-old Selmayr, Juncker's former chief of staff, on February 21.

During a single meeting of commissioners, Selmayr was made first deputy secretary general and then just minutes later secretary general when the incumbent, Alexander Italianer, suddenly announced his retirement.