European Commission President Jose Manuel Barroso has handed over all his antitrust duties to Internal Market Commissioner Charlie McCreevy.
Mr Barroso had been responsible for EU antitrust cases that could not be handled by Competition Commissioner Neelie Kroes due to possible conflicts of interest.
"President Barroso has decided to refer to Commissioner McCreevy responsibility for competition dossiers which Mrs Kroes cannot deal with," Commission spokeswoman Francoise Le Bail said.
"They have now been reallocated and it will be Mr McCreevy who will be making decisions on those dossiers," Ms Le Bail said.
Mr McCreevy was chosen because he did not cover a sector and had good knowledge of industry and the internal market, she added. "Mr McCreevy was the obvious candidate for this."
Under commission policy, once Ms Kroes disqualified herself, Mr Barroso had the choice of handling the files himself or handing them over to other commissioners.
Mr Barroso sparked controversy over his handling of shipping antitrust cases after it became public that he and his family spent six days in August on the yacht of Greek shipping tycoon Spiro Latsis.
Seventy-seven MEPs alleged a company owned by Mr Latsis later won commission approval for a €10 million state aid package.
Ms Kroes withdrew from shipping cases because she used to sit on the board of shipping company P&O Nedlloyd.