LONDON (Reuters) - The world's leading outdoor advertising groups JCDecaux and Clear Channel have agreed to measures designed to open up the market for advertising on bus shelters and other street furniture, Britain's Office of Fair Trading (OFT) said on Thursday.

The OFT said the companies had agreed to measures such as not enforcing exclusivity clauses preventing competitors placing other adverts nearby and not enforcing renewal clauses that cause contracts to be rolled over automatically.

The regulator also said it had issued guidance to local authorities on how best to award contracts and encourage stronger competition.

The OFT said it had found no infringements of competition law and that the assurances received from the companies meant it had now closed its investigation into street furniture advertising contracts.

(Reporting by Paul Hoskins; Editing by Rhys Jones)