DirecTV Group Inc. has asked the Federal Communications Commission to block the planned purchase of bankrupt Adelphia Communications Corp. by Time Warner Inc. and Comcast Corp.

“These transactions will create regional monopolies of the size and scope never before approved by the commission, enhancing the already considerable market power of the country’s two largest cable incumbents,” El Segundo-based DirecTV said in a complaint it filed Thursday with the FCC.

The purchase of Adelphia for $17.6 billions would add 5.2 million subscribers to the rolls of Time Warner and Comcast, the nation’s two largest cable operators.

It would also make Time Warner’s cable division the largest operator in Los Angeles and New York City.