PARIS (Reuters) - The French government called on former European Commission chief Jose Manuel Barroso on Wednesday to drop plans to take a senior job at U.S. investment bank Goldman Sachs, part of a growing outcry against the move.

The bank said last week it had hired Barroso, a conservative Portuguese ex-premier who headed the European Union's executive arm from 2004-2014, to be an adviser and non-executive chairman of its international business.

French European Affairs Minister Harlem Desir said the "scandalous" move raised questions about the EU's conflict of interest rules and said they needed to be tightened.

"It's a mistake on the part of Mr. Barroso and the worst disservice that a former Commission president could do to the European project at a moment in history when it needs to be supported and strengthened," Desir said during a question and answer session in the lower house of France's parliament.

Barroso was hired 20 months after stepping down, shortly after an 18-month "cooling off" period when ex-commissioners must seek clearance for new jobs to avoid conflicts of interest.

"The European Commission president should be above the pressures of private interest. The restriction on being hired by a private company should be extended," Desir said.

In reaction to news of Barroso's move, the European Ombudsman called on Tuesday for the EU to tighten rules on commissioners taking appointments on leaving office.

EU Economics Commissioner Pierre Moscovici criticized the appointment as bad for the Commission's image at a time when it is under attack as Britain prepares to leave the European Union.

"When a public person leaves public life and goes to the private sector, he also has to think about the image it projects," Moscovici said on France's Europe 1 radio.

"I can assure you I won't go to Goldman Sachs," he added.

Barroso has said he aims to bring his experience in EU affairs to help the bank prepare for Britain's departure from the bloc.

He was president of the Commission, which polices EU countries' public finances, when it came to light that Goldman had helped Greece in the past to reduce its debt burden with cross currency derivatives, worsening its debt crisis.

(Reporting by Leigh Thomas; editing by Michel Rose and Gareth Jones)