UPDATE 1-Private equity firm Triton bids for Karstadt

* Demands further concessions from lessors, staff

* Creditors to meet this weekend amid doubts -sources

* Administrator to evaluate offer as soon as possible (Recasts; adds details, background)

FRANKFURT, April 23 (Reuters) - European buyout firm Triton offered to acquire insolvent German department store chain Karstadt in its entirety, submitting the one and only bid to the court-appointed administrator by the Friday deadline.

Triton said it presented a strategic concept to continue operating the chain as a going concern, but warned it would need Karstadt’s lessors and its staff to make more sacrifices before the acquisition plans could proceed.

“We need a cooperation on the basis of further concessions in order to make a sustainable restructuring possible,” a Triton spokesman said.

Two financial sources said the most important creditors of Karstadt, including the property owners of the 120 stores, would meet to discuss the Triton offer amid doubt over whether they or delegates of the 26,000 employees would accept the terms.

Karstadt department stores can be found in the center of virtually any large German city, and the chain’s collapse during the 2009 recession made it the best known company to fall victim to a wave of bankruptcies.

Parent Arcandor AG AROG.DE imploded early in June after management failed to extract a state bailout just after cash-strapped Opel was rescued by the German government. [ID:nL9454449].

Many observers blame Arcandor’s failure on long-time Chief Executive Thomas Middelhoff, who divested all of Karstadt’s properties in sale-and-leaseback deals with several real estate firms, one of which counted Middelhoff as investor.

The leasing rates were in some cases so punitive that many believed they were a key catalyst of Arcandor’s financial problems.

Behind Triton’s offer is Johannes Maret. The 59 year-old manager worked as an investment banker between 1996 and 2002 for the now defunct private bank Sal. Oppenheim, which itself was a major investor in Arcandor.

Administrator Klaus Hubert Goerg said on Friday he would examine the one offer he received as soon as possible, declining to reveal the name of the interested party.

“The goal was and still is, to sign a purchase contract as soon as possible,” Goerg said. (Reporting by Christiaan Hetzner, editing by Gerald E. McCormick)