The head of French oil company Total SA (TOT) said Friday he believed the companies being investigated as part of a European Commission probe into alleged oil-price manipulation weren't involved in such activities.

On Tuesday, European Union antitrust authorities carried out unannounced inspections of energy companies BP PLC (BP), Royal Dutch Shell PLC (RDSA) and Statoil ASA (STO), escalating a probe amid scrutiny of how prices are set in global financial markets.

EU officials are investigating whether the three companies manipulated prices in the $2.5 trillion physical-oil market by giving false data to an oil index publisher, the Platts unit of McGraw Hill Financial Inc. (MHFI). Platts's offices were also inspected Tuesday.

The companies involved confirmed their offices had been inspected and that they were cooperating with the investigation.

ENI SpA (E) of
Italy said it had been asked for information by commission investigators but that its offices hadn't been searched.

"When one knows the companies in question, I'd be really very surprised they took part in price rigging," Total chairman and chief executive Christophe de Margerie told reporters on the sidelines of the company's annual shareholders meeting in
Paris .

Mr. de Margerie insisted that Total, which had raised some issues during an pan-oil industry consultation last year, hadn't been the whistleblower in the commission's probe.

When asked if the company had complained to the commission, Mr. de Margerie replied: "We haven't sent any letter." Total isn't being investigated as part of the EU probe, he reiterated.

Mr. de Margerie also said that overall, the price reference system was working satisfactorily even if there had been minor glitches and he didn't believe the EU probe would reveal a huge scandal.

Were the commission to uncover evidence of collusion in reporting distorted prices or engaged in other anticompetitive practices, such as potentially distorting prices by preventing others from participating in the price assessment process, it could impose substantial fines.