The officials' verdict will decide whether the 25-year-old, whose lower leg is amputated, can compete in next month's European athletics championship in Zurich.
Rehm jumped 8.24 metres at the German athletics championship in Ulm, setting a new world record for long jumpers with a disability.
He not only beat his own previous record by 29 centimetres but also formally qualified for the European tournament.
German sports officials started reviewing the case after Rehm's victory. The German Athletics Association (DLV) said it will announce on Wednesday whether it would nominate the long jumper for Zurich.
The DLV said it wanted to wait for the results of tests that would clarify whether Rehm's prosthesis had given him an unfair advantage over non-disabled athletes.
Regardless of the outcome of the tests, German athletics coach Uwe Florczak did not commit to nominating Rehm on the weekend. He said that despite his "great respect" for Rehm, he had concerns about the long jumper's abilities.
"I have seen many jumps over eight metres. The run-up speed [of Rehm] was not as high as what we know for these jumps," Florczak said.
He also said he had seen that "the prosthesis had yielded a lot and then rebounded".
Pistorius no precedent
"We slept through this," Florczak added. "We should have reviewed earlier whether the prosthesis was an improper aid."
One competitor raised the possibility that Rehm had won unfairly.
"I do not know too much about the issue but I know that his prosthesis is 15 centimetres longer than his healthy leg," former European champion Sebastian Bayer said who placed fifth in Ulm said. "My jumping leg is as long as my other leg."
The European Athletics Association (EAA), meanwhile, said it would not rule on whether Rehm could compete in Zurich.
"The European association cannot make this decision, that has to be done by the world association IAAF," EAA General Secretary Christian Milz said.
Milz said Oscar Pistorius's participation in the London Olympic Games in 2012 was not a precedent for Rehm's case. Pistorius was only allowed to compete after suing successfully before the Court of Arbitration for Sport (CAS).
Rehm acknowledged that his victory created headaches for sports officials.
"They will have to put some thought into this. I have caused a lot of people to scratch their heads," he said.
He denied that the prosthesis had given him an unfair advantage, saying it was three to four centimeters – instead of fifteen centimeters – longer than his other leg because it was flexible and yielded during the spring.
"I think it doesn't give me an advantage or a disadvantage. The prosthetic is replacing what I don't have anymore," he added.
Despite the uncertainty for her protégé, Rehm's coach Steffi Nerius welcomed the debate. "I hoped that he would qualify for the European championships so this will be discussed to the end," she said.
Nerius defended her athlete.
"He has as many disadvantages as he has advantages," she said. "The first disadvantage is that he is amputated below the knee. I am happy that I still have my lower leg."
Rehm lost his lower right leg in a wakeboarding accident.
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