The European Commission has started a formal antitrust investigation against technology major IBM Corp for allegedly abusing its market dominance in mainframe computers.

The Commission today said it will probe IBM in two separate cases, both of which are related to the company's conduct in the market for mainframe computers.

Mainframes are those computers used by many large companies and government institutions worldwide to store and process critical business information.

In a statement, the antitrust agency said the first case follows complaints by emulator software vendors T3 and Turbo Hercules, regarding allegations that IBM engaged in "illegal tying of its mainframe hardware products to its dominant mainframe operating system".

"The second is an investigation begun on the Commission's own initiative of IBM's alleged discriminatory behaviour towards competing suppliers of mainframe maintenance services," the EC noted.

Last year, about 8.5 billion euros were spent on new mainframe hardware and operating systems while such expenditure stood at 3 billion euros for the European Economic Area.

According to the statement, the initiation of proceedings does not imply that the Commission has proof of infringements but only "signifies that the Commission will further probe the cases as a matter of priority".

Moreover, the Commission has concerns on whether IBM engaged in anti-competitive practices with a view to foreclosing the market for maintenance services--keeping potential competitors out.