Traditional media companies with the most experience in selling advertising should look to buy online groups, such as social networks, to gain online audience numbers and an international outlook, leading Internet investor Saul Klein, of Europe's Index Ventures firm, told the Reuters Technology, Media and Telecoms summit in Paris Wednesday, Reuters reported.

If newspapers want to find new audiences, they will need to look to online, mobile and social media companies, he said.

“New audiences are not in newspapers or on TV or radio. They're online and on mobile and in social media companies,” said Klein, Reuters reported. Additionally, European firms need to start competing with U.S. companies for deals that combine their ad sales teams with social networks' growing audiences, he said.

Social media networks have grown exponentially, “but without a sales force you're just not going to generate significant revenues and explain to advertisers what the opportunities are,” he said, according to Reuters.

U.S. companies aren't timid to buy European start-ups, he said, citing eBay's purchase of online telephony group Skype, which was developed in Estonia, as one example.