Clear Channel Outdoor has acquired the UK Van Wagner business, which operates 70 premium-format outdoor advertising sites in London.
The acquisition will strengthen Clear Channel's offering with the addition of Van Wagner's large-format Mega-96-sheet and Mega-six-sheet products.
Clear Channel will also gain Van Wagner's portfolio of backlit 96-sheet billboards and a range of special-build billboard sites.
Neither party would confirm the value of the deal, which is thought to be worth several million pounds.
Specialist outdoor agencies, which buy space from outdoor media owners, have welcomed the move.
James Copley, Kinetic's UK client development director, said the deal would "substantially improve Clear Channel's offering in London from a strategic point of view".
He said: "When Van Wagner first entered the market, it introduced a very aggressive policy with its super-sign policy. This made other media owners pull their socks up, but in the past 18 months we haven't seen any major new developments." Copley added that he hoped Clear Channel would continue to sell Van Wagner's sites on an individual line-by-line basis.
Barry Sayer, the interim chief executive of Clear Channel UK, said: "The acquisition will enhance the quality of Clear Channel's UK product, with 70 sites in the most prestigious locations across the capital, including the LED screen in Piccadilly Circus and sites at London Bridge and the M4."
Clear Channel's US head office has questioned some of the UK division's practices in the past. In March, Paul Meyer, the global president of Clear Channel Outdoor, called the remuneration system in the UK "flawed".
Clear Channel's other brands include Adshel, Taxi Media and Clear Channel Billboards.
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