LISBON - Portugal's prime minister said he had called for "clarifications" from European Commission head Jean-Claude Juncker that there would be no "discriminatory treatment" of his EC predecessor Jose Manuel Barroso, whose decision to work for Goldman Sachs has sparked controversy.

"I asked for clarifications from the president of the Commission on the decision taken in relation to Mr Barroso," said Antonio Costa, quoted by the Portuguese news agency Lusa, on the margins of Friday's EU summit in Bratislava. "We must ensure that there is no discriminatory treatment" in particular "compared to other former members of the commission who might be in similar situations," prime minister Costa said.

Former commission head Barroso, prime minister of Portugal from 2002-2004, earlier this week accused Brussels of discrimination after it ordered an ethics probe into his new role at US investment bank Goldman Sachs.

"Not only are these actions discriminatory but they appear to be inconsistent with decisions taken in respect of other former members of the Commission," Barroso said in a letter to Juncker, who succeeded him in the top Brussels job. In his sternly-worded letter dated Tuesday, Barroso deplored claims "that the mere fact of working with Goldman Sachs raises questions of integrity."

These "baseless and wholly unmerited" claims are "discriminatory against me and against Goldman Sachs", he said.

The probe, which Juncker notified to the European Union's official watchdog on Monday, marked a significant U-turn by the Commission which had previously defended Barroso. Juncker also said Barroso will now be received at the Commission, the executive arm of the 28-nation bloc, as a simple lobbyist rather than with the pomp and protocol due a former head.

Barroso said he took particular offence to the "specific suggestion ... that Goldman Sachs is employing me as a lobbyist and adviser in relation to the forthcoming Brexit discussions."

"I have not been engaged to lobby on behalf of Goldman Sachs and I do not intend to do so," Barroso said.

French President Francois Hollande has previously attacked Barroso's appointment at Goldman Sachs as "morally unacceptable".

Goldman Sachs was heavily involved in selling complex financial products, including high-risk sub-prime mortgages that many blame for causing the global financial crisis in 2008.

Critics believe the company was also key to the complex finance mechanisms that helped Greece hide the true state of its public finances in the lead-up to the debt crisis.

Barroso headed the Commission from 2004 to 2014, overseeing membership for several former communist states in Eastern Europe, the response to the global financial crash and the ensuing eurozone debt crisis.