UPDATE 1-United Internet says won't fold in freenet poker

(Adds CEO comment, share price, Freenet reaction)

FRANKFURT, May 7 (Reuters) - United Internet (UI) (UTDI.DE), Germany's second-largest Internet service provider, is seeking a court order to block domestic rival freenet's plan to acquire mobile firm Debitel, UI's chief executive said on Wednesday.

United Internet, a major shareholder in freenet (FNTG.DE), is fiercely opposed to the plan, arguing it is not in the interest of a majority of shareholders, but freenet agreed last week to buy the larger Debitel for 1.63 billion euros.

Having failed to block the deal with a sweetened bid for freenet, United Internet has now filed for an injunction to stop freenet from issuing new shares, which Debitel's owner, private equity firm Permira, is due to receive in the sale.

United Internet CEO Ralph Dommermuth told Reuters in an interview on Wednesday a court hearing on May 22 will rule whether freenet has the right to issue new shares.

Freenet said it assumes United Internet's bid for a court injunction will not succeed.

Dommermuth also said United Internet will also seek a court order allowing it to call a freenet shareholder meeting.

"It's May and freenet has yet to invite shareholders for its annual general meeting, that's a breach of stock corporation law," Dommermuth said.

United Internet had wanted to split up freenet, keeping the Internet business and letting its joint venture partner Drillisch AG (DRIG.DE) have the mobile telecoms part.

Dommermuth said the company may still buy freenet's DSL business.

"If freenet puts its DSL business up for sale, we will surely make a bid. We're not sulking," he said.

Freenet has said it wants to divest its DSL broadband division to focus on its mobile business.

Dommermuth also said the company exceeded its target in the first quarter of the year and may adjust its full year targets after the first half 2008.

United Internet expects sales, core profit and earnings per share to grow 20 percent this year.

In the January-March quarter United Internet posted a 31.2 percent gain in core profit of 83.2 million euros on sales of 402 million euros, up 19.3 percent.

Net income was up 46 percent at 45.1 million euros, the company said, adding fee-based customer contracts grew to 7.46 million as of March 31 from 6.55 million in 2007.