COLOGNO MONZESE, Italy, Nov 29 (Reuters) - The leading investor in ProSiebenSat.1 said the German broadcaster was underperforming and should look to cash in on its digital and e-commerce businesses to focus more on TV and entertainment.

"The situation in Germany is complicated due to a challenging economic environment ... but the ProSiebenSat TV business is performing below the market," MFE-MediaForEurope CEO Pier Silvio Berlusconi told reporters at a press briefing on Wednesday.

MFE, which began investing in Prosieben in 2019 and now holds a 29% stake in its German peer, has repeatedly said it considers its investment as strategic as part of its ambition to build a pan-European TV platform.

ProSieben has expanded beyond its core TV business to operate sites which provide a range of services, from online dating to e-commerce.

The MFE boss, the son of the late former Italian Prime Minister Silvio Berlusconi, said the German group should seek to monetise its digital and e-commerce operations as far as possible to reinvest proceeds in its core business.

ProSieben said earlier this month it expected its full-year revenue to fall slightly below its target range due to a weaker advertising business and its shares have fallen more than 30% this year.

In April it slashed its dividend for 2023 as it announced a nearly 20% drop in 2022 operating profit.

Berlusconi said the MFE plan for a pan-European platform was attracting interest from national broadcasters, including from Portugal and other bigger European markets.

The broadcaster, which also operates in Spain, sought to buy France's peer M6 last year.

"We received expressions of interest from Portugal but also larger markets," he said, without elaborating, at the company's Italian headquarters near Milan.

MFE sees European expansion as the way to resist the increasing dominance of U.S. streaming giants such as Netflix , and to help offset the flight of advertising budgets to companies such as Facebook. (Reporting by Elvira Pollina Writing by Keith Weir; editing by David Evans)