The 31-year-old Belarusian tested positive for metenolone, an anabolic agent, meaning New Zealander Valerie Adams' medal will be upgraded from silver to gold.
Ostapchuk alleged to Belarusian newspaper Pressball, translated by website Charter 97, that Anatoly Baduyev, the country's former athletics head coach, could be behind her positive test results.
The former coach was arrested by the country's KGB in May on suspicion of embezzlement following reports that an official was extorting money from athletes through the threat of positive drug tests.
"The person, you know who I mean, the one who was involved in blackmail, he promised me long ago: You will have problems with doping control. Now I think his threat begins to come true, even though he no longer works with us," Ostapchuk said.
"Anything that will be learned during the investigation will be known to everyone. I have nothing to hide from people. I've spent a lot of efforts to become an Olympic champion, I do not need excuses. I do not want to finish career like this."
Meanwhile, the aide to the President of Belarus for physical education, sport and tourism Igor Zaichkov has said Belarus will fight for the gold medal.
"Both samples, A and B, tested positive. We will try to find out what happened and will investigate into the matter...we will fight for Nadezhda Ostapchuk's medal and defend her interests, Zaichkov told BelTa.
Yesterday, Ostapchuk said she was also going to fight the drug-test findings.
"I was tested twice more in London but I don't have any idea how this thing ended up in my body. I'm going to fight this allegation because it can't be possible," Ostapchuk reportedly told local media in Minsk.
"In total, I've been tested 16 times since April. You must be a complete idiot to take doping just before the competition especially such an outdated drug as a steroid, knowing you're going to be tested not once but probably several times."
Drug Free Sport New Zealand executive director Graeme Steele told APNZ the metenolone steroid found in Ostapchuk's system was an old-fashioned doping substance which, in comparison to other performance enhancing drugs, could easily be detected in testing.
"There is some validity [and] sense in what she is saying," he told APNZ.
"It is an old-style anabolic steroid and it's very surprising that any athlete would allow that type of drug to still be in their system when they arrived at the Games because it's quite easy to detect."
