An EU ethics committee has cleared former European Commission chief Jose Manuel Barroso of breaking rules by taking a job at Goldman Sachs but said he did not show the "considerate judgment" one would expect from someone of his stature.

The Portuguese ex-premier caused an uproar when he joined the U.S. investment bank as an adviser for Brexit, with critics saying it further diminished public confidence in the European Union in the wake of Britain's damaging vote to leave the bloc.

European Commission President Jean-Claude Juncker launched an unprecedented ethics investigation in September to determine whether Barroso had breached the executive Commission's code of conduct.

"There are not sufficient grounds to establish a violation of the duty of integrity and discretion ... with regard to the acceptance by former President Barroso of the positions of non-executive chairman ... and adviser in relation to (Goldman's) business with its clients," the Ethical Committee said.

But in its decision, published on Monday, the panel also said Barroso "has not shown the considerate judgment one may expect from someone having held the high office he occupied for so many years".

The opinion failed to satisfy the EU's ethics watchdog, European Ombudsman Emily O'Reilly, who said she would weigh what steps to take, including opening an inquiry into the affair.