The German government wants additional assurances before giving its support to a special state-backed loan for Arcandor's mail order unit Quelle, Economy Minister Karl-Theodor zu Guttenberg said.
Germany has been discussing whether to back a loan of around 50 million euros ($70 million) to keep Quelle alive after parent company Arcandor filed for bankruptcy.
Hopes for a deal have been repeatedly raised over the last few days only to fade again.
Economy Minister Guttenberg said the government still needed more details before committing to a deal.
A special state-backed loan (Massekredit) is an option but for that we need certain assurances, Guttenberg told reporters.
Ministry officials had told Reuters late on Wednesday that a statement on the guarantees was imminent, but Guttenberg's comments showed there were still issues to be worked out.
Arcandor, which also owns the Karstadt chain of department stores and a majority stake in UK-based travel group Thomas Cook, filed for insolvency earlier this month after the government rejected two successive appeals for state aid.
Arcandor's priority now is to shore up Quelle, which needs cash to publish its new catalogue for the fall/winter season and to order new goods.
The Bavarian state premier Horst Seehofer said that Bavaria and Saxony were ready to give half of the 50 million euros that Quelle says it needs.
Martin Zeil, the economy minister from the southern state of Bavaria, where Quelle is based, criticised the conflicting signals coming from Berlin.
I really regret the constant problems and that the agreement, which we thought had been sealed, has now been called into question again, Zeil told a Bavarian radio station on Thursday.
Ernst Sindel, the top worker representative at Quelle, told the same radio station that technical issues had held up the deal, saying the state guarantees would definitely come. An insolvency advisor overseeing Quelle, also said he thought the government wanted to do a deal.
The German government rejected Quelle's original request for help on Monday, but the company has submitted a revised plan which it hopes the government will back. ($1=.7106 Euro)
(Writing by Marc Jones and Noah Barkin; Editing by Will Waterman and Jon Loades-Carter)