Porsche rejected Saturday an ultimatum from Volkswagen to accept humiliating rescue terms and a takeover within two days or else face bankruptcy, according to dpa. The German sports car maker last year made an ill-fated bid to take over Volkswagen. After changing from hunter to prey, it is looking for a safe way to extract itself using a cash infusion from the Qatar Investment Authority (QIA). The magazine Der Spiegel cited industry sources saying Volkswagen and the state of Lower Saxony had told Porsche that the bigger car company's rescue offer would expire on Monday if Porsche did not indicate acceptance. In a written response, Porsche board chairman Wolfgang Porsche replied: "We won't let ourselves be blackmailed. "It sullies the cause. These are not the manners that encourage a spirit of togetherness." He said Porsche sought a joint and successful shared future with Volkswagen, and was annoyed by Volkswagen's choice of words. "Ultimatums never achieve anything," he added, calling on "the initiators" to "calm down and pursue their proposals in closed-door talks, not via headlines." Porsche SE, owned by the Porsche and Piech families, has debts of 9 billion euros (13 billion dollars) and holds 51 per cent of Volkswagen, but without having obtained management control. Spiegel said Volkswagen now proposed to buy a 49-per-cent stake in the Porsche factories and brand for 3 to 4 billion euros, let QIA take over Porsche's VW stock options and finally merge VW with the Porsche SE parent. The families would own just over 40 per cent of the merged group, with QIA holding 15, another sovereign investment fund 5 and the state of Lower Saxony holding 20 per cent. The rest of the stock would be traded. Der Spiegel said that board head Porsche and Porsche chief executive Wendelin Wiedeking were warned that if they refused Volkswagen, the bigger company would in September recall a loan of 700 million euros to Porsche, bringing the sports-car maker to it knees. On Friday, Porsche insisted that its preferred rescue option, a purchase by QIA of a minority stake in Porsche SE, was on track, with due-diligence checks of its books complete.