LONDON--The U.K. Office of Communications, or Ofcom, said Thursday most of the fixed retail call markets in the U.K. remain effectively competitive, but BT Group PLC (BT.A.LN) has 'significant market power' in wholesale call origination in the U.K. and in fixed call termination, excluding the Hull area.

The telecommunications regulator has therefore imposed remedies including charge controls on BT in these markets, and in relation to interconnect circuits, it said.

Ofcom said KCOM PLC (KCOM.LN) has significant market power in the market for wholesale call origination in the Hull Area, and has also imposed a series of remedies in this market and to interconnect circuits.

BT shares closed Wednesday at 343 pence, valuing the company at 27.09 billion pounds ($43.38 billion); KCOM shares closed at 91 pence, valuing the company at GBP467.53 million.

Write to Ian Walker at ian.walker@wsj.com

Subscribe to WSJ: http://online.wsj.com?mod=djnwires