European Commission President Jean-Claude Juncker has been asked to clarify the EC's position on his predecessor taking a role at Goldman Sachs International (GS - Get Report) and whether it poses a conflict of interest.

The request, from European Ombudsman Emily O'Reilly, concerns Jose Manuel Barroso's recent appointment as a non-executive chairman and adviser at the U.S. investment bank.

Barroso served as prime minister of Portugal from 2002 to 2004 and as EC President for two consecutive terms, from 2004 until 2014.

Some European Union politicians and transparency campaigners have raised objections to Barroso's new posting.

Corporate Europe Observatory, a Brussels-based group that campaigns against the power of corporations and lobbies, has called Barroso's move "scandalous."

It has also called for toughening up rules for ex-Commissioners and the so-called 'revolving doors' between the public and private sectors.

On Tuesday, European Ombudsman O'Reilly stepped into the fray, asking the EC president to explain what measures it has taken to check whether the appointment conforms with ethics obligations in the EU Treaty, and whether the EC is thinking about reforming the Commissioner's Code of Conduct.

While "many of the activities taken up by former commissioners go largely unremarked," O'Reilly writes, "your predecessor's action has generated understandable international attention given the importance of his former role and the global power, influence and history of the bank with which he is now connected."

She also points to "public unease" over Barroso's public remarks that he will in his new role be advising on the U.K.'s decision to leave the 28-country European Union.

Speaking to journalists in Brussels early Tuesday afternoon, an EC spokesman said the Commission's code of conduct rules against conflicts of interest "are the strictest rules in the world in this respect," and that they were fully respected.

The spokesman also noted that Barroso's appointment came more than 18 months after he left office, in accordance with the code. "Everything which has been done is based on a legal services opinion," he said. "We have not done anything which has not been given prior approval by our lawyers."