European Union competition regulators launched two antitrust probes Monday against International Business Machines Corp., suspecting it of abusing its dominant position on the mainframe computer market.

One investigation followed complaints by emulator software vendors T3 and Turbo Hercules against IBM’s practices and focuses on the U.S. computer giant’s alleged tying of mainframe hardware to its mainframe operating system.

The second probe, opened on the European Commission’s initiative, concerns alleged discriminatory behavior toward competing suppliers of mainframe maintenance services.

“The Commission has concerns that IBM may have engaged in anticompetitive practices with a view to foreclosing the market for maintenance services … in particular by restricting or delaying access to spare parts for which IBM is the only source,” said the commission, which enforces the EU’s competition rules and can fine companies that break them.

Mainframes are powerful computers used by many large companies and government institutions worldwide to store and process critical business information, with the vast majority of corporate data worldwide residing on mainframes.

In 2009 approximately 8.5 billion euros ($10.97 billion) worldwide and 3 billion euro in the European Economic Area were spent on new mainframe hardware and operating systems.

The Commission said T3 and Turbo Hercules had alleged IBM had been illegally tying its mainframe hardware products to its dominant mainframe operating system.

According to the complaints, the tying shuts out providers of emulation technology which enable the users to run applications on non-IBM hardware.