BRUSSELS — The European Union fined Intel a record $1.45 billion today and ordered the world's biggest maker of computer chips to stop illegal sales tactics that shut out Silicon Valley rival AMD.

The fine, which exceeded a monopoly abuse penalty imposed on Microsoft last year, was denounced by Intel, which plans to appeal to an EU court within 60 days.

AMD's stock jumped in midday trading today, while Intel shares were up slightly.

"Given that Intel has harmed millions of European consumers by deliberately acting to keep competitors out of the market for over five years, the size of the fine should come as no surprise," said EU Competition Commissioner Neelie Kroes.

"Intel did not compete fairly, frustrating innovation and reducing consumer welfare in the process," she said.

The European Commission also told Intel to immediately cease some sales practices in Europe, though it refused to say what those were. Intel said it was "mystified" about what it was supposed to change but would comply with the "extremely ambiguous" EU order.

Intel, based in Santa Clara, Calif., has about 80 percent of the world's personal computer microprocessor market and faces just one real rival, Advanced Micro Devices, which has its headquarters just three miles from Intel in Sunnyvale, Calif.

The two companies have been fighting for years over what AMD claims is Intel's intimidation of computer makers into striking exclusive deals for the chips they use in their new machines.