By Klaus Lauer and Alexander Hübner

BERLIN (Reuters) - Czech investment group PPF on Monday launched a bid to lift its stake in German broadcaster ProSiebenSat.1 to just under 30%, countering plans by MFE-MediaForEurope to tighten its grip on the firm.

MFE, which is owned by the Berlusconi family and has commercial TV operations in Italy and Spain, made a low-ball bid for ProSieben in March as part of a push to create a pan-European broadcaster - a move resisted by the German firm, which is striving to remain independent.

PPF, whose 14.94% stake in ProSieben makes it the second-biggest shareholder after MFE with 30.14%, said on Monday it will buy ProSiebenSat.1 stock at 7 euros ($7.85) per share, with an aim of achieving a stake of up to 29.99%.

Shares in ProSiebenSat.1 were up 17.4% at 7 euros in Frankfurt, matching the offer. PPF said in a statement the offer represents a 17% premium over the closing price on Friday and a 21% premium to the price implied by MFE's bid.

ProSieben's executive board welcomed the move. "It will provide shareholders, who prefer to monetize their investment short-term, with a better all-cash alternative to the public takeover offer published by MFE," it said.

Intesa Sanpaolo analyst Antonella Frongillo said the PPF counteroffer complicates MFE's plans to take control of PSM. "In our opinion, all these moves are aimed to force MFE to withdraw from its German campaign," she wrote in a note.

Equita analyst Milo Silvestre said that following PPF's offer, "we believe... take-up of MFE's offer (approximately 5.78 euros per share at current prices) is unlikely". He said one option for MFE was to reassess its bid.

MFE declined to comment. It said last week that it did not expect to get a majority in ProSieben.

MFE, which has already crossed the 30% threshold which normally triggers a 100% takeover offer under German law, will have the option to buy additional shares from the market after the end of its offer in June.

PPF's Chief Investment Officer Didier Stoessel told Reuters that while his group is not at this stage thinking of going above the 30% stake that would trigger a mandatory offer, it will seek three seats on ProSieben's supervisory board.

This would mean one additional seat to one representative and one independent nominated by PPF on the board now.

Stoessel said PPF's aim was to speed up the German group's transformation, and that it was willing to engage with all other shareholders.

"It's about transforming a linear broadcaster to a digital media (firm) - much quicker than they have done in the last few years," Stoessel said in an online interview.

($1 = 0.8913 euros)

(Reporting by Klaus Lauer, Alexander Huebner, Isabel Demetz and Elvira Pollina; Additional reporting by Jan Lopatka; Writing by Jan Lopatka; Editing by Friederike Heine, Ludwig Burger and Jan Harvey)