Dhaka, April 18 -- Alphabet's Google illegally dominates two markets for online advertising technology, a judge ruled on Thursday, dealing another blow to the tech giant and paving the way for US antitrust prosecutors to seek a breakup of its ad products.

US District Judge Leonie Brinkema in Alexandria, Virginia, found Google liable for "willfully acquiring and maintaining monopoly power" in markets for publisher ad servers and the market for ad exchanges which sit between buyers and sellers.

The decision clears the way for another hearing to determine what Google must do to restore competition in those markets, such as sell off parts of its business at another trial that has yet to be scheduled. It is the second court ruling that Googl...