AMSTERDAM—Saab Automobile's future was again in doubt Thursday after owner Spyker Cars NV said a €150 million ($213 million) investment agreement with a Chinese auto maker had fallen apart.

The announcement puts Saab Chairman and Spyker Chief Executive Victor Muller under intense pressure to come up with another deal quickly. Saab's plant in Trollhattan, Sweden, has been idle since production was halted six weeks ago after suppliers stopped delivering parts because they hadn't been paid.

Netherlands-based...