MADRID, July 3 (Reuters) - Spain's Prisa and rival Mediapro (Imagina) will continue taking about a possible deal to pool their TV and radio assets for another three weeks, Prisa said on Friday.

Prisa, owner of TV channel Cuatro, said it and Mediapro had set a new deadline of July 24 for the talks to conclude, after a previous deadline set a month ago expires on Saturday.

A merger of Prisa's TV and content interests with those of Mediapro, which has a controlling stake in TV channel La Sexta, would help offset a global slump in advertising revenues.

An agreement would also help to ease investor worries about Prisa, which has a 5 billion euro debt burden and has been trying to make its business more efficient and modern. It has cut staff pay and suspended dividends as part of a restructuring plan, and does not rule out having to increase capital.

(Reporting by Ben Harding and Elisabeth O'Leary; editing by Simon Jessop) Keywords: PRISA/

(elizabeth.oleary@reuters.com; +34 91 585 8295; Reuters Messaging: elizabeth.oleary.reuters.com@reuters.net;)

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