HAMBURG/FRANKFURT (Reuters) - The insolvency administrators of German DIY store chain Praktiker (>> Praktiker Bau und Heimwerkermaerkte AG) have stepped up the search for an investor by appointing Macquarie (>> Macquarie Group Ltd) as advisor and asking for bids by September, they said on Tuesday.

The administrators hope that by finding an investor quickly they can secure as many jobs and stores as possible at the group, which has around 20,000 full and part-time employees.

The group filed for insolvency earlier this month for the Praktiker-branded units, before its more successful Max Bahr chain followed last week. Max Bahr is expected to be of more interest to investors.

"Max Bahr, in particular, is an established brand that is working and there is also interest in Praktiker," the administrators said in a statement on Tuesday.

The administrators said at a press conference in Hamburg that they aimed to sell as many of the stores as possible in a package, with any buyer for Max Bahr taking on some Praktiker stores. Furthermore, any investor should be prepared to pump in at least 100 million euros ($132.5 million).

"We believe that a more inclusive offer will bring better results," said Jens-Soeren Schroeder.

Sources told Reuters last week there had already been interest from private equity.

Around 300 stores affected by the insolvency would continue trading for now and talks are ongoing over a loan to keep them permanently open, the administrators said.

Praktiker, whose blue and yellow stores are a familiar sight in German out of town shopping centres, ran into difficulties after scrapping its popular "20 percent off everything" discounts. The long winter compounded its problems and forced it to file for insolvency earlier this month.

Pay for the 14,000 of the group's employees affected by the insolvency has been secured until the end of September. A report over the weekend suggested 4,000 jobs could go and a dozen stores could soon be closed.

The administrators said on Tuesday it was too early to provide information on individual stores. Of the 300 stores in the insolvency process, 168 are Praktiker stores, 78 are Max Bahr stores and a further 54 are Praktiker-branded shops that have recently been converted to the Max Bahr signage.

(Reporting by Jan Schwartz and Victoria Bryan; Editing by Louise Heavens)