May Myat Noe, 16, was training to become a K-pop star in South Korea after winning the Seoul-based Miss Asia Pacific World beauty pageant in May.
But last week the organisers stripped her of the title for alleged dishonesty, accusing her of absconding with the crown and the $10,000 implants, which they say they funded to enhance her budding singing career.
On Tuesday the beauty queen hit back and demanded an apology from the organisers.
"It is natural for me to feel that an apology should be demanded to rectify the damage they have done to the integrity of my country," she told a packed press conference in Yangon.
"I will return the crown only when they apologise to Myanmar, for the dignity of our country."
May Myat Noe also denied accepting free breast implants.
"I was put under duress to undergo head-to-toe cosmetic surgery which I refused... I didn't have breast implants, but I don't want to go into details, to preserve my dignity," she said.
Her comments appear to have deepened the acrimony between pageant organisers and their former queen.
Young Choi, founder of Miss Asia Pacific World, told AFP the organisers had photographic evidence of the breast implant operation and that they would consider legal action against May Myat Noe.
"She has been lying. She also lied at today's news conference. She must return the crown," he said, declining to give the cost of the tiara but explaining it was made over several weeks by ten specialists.
"It's not for us but for her to apologise. She has been hurting our image and credibility," he said in Seoul.
Choi said his organisation hoped to handle the sensitive matter "quietly in consideration of relations between South Korea and Myanmar" but was ready to consider a lawsuit "if she refuses to cooperate."
Myanmar women are eyeing success in international beauty pageants as the country opens up after decades of military rule.
Despite undergoing sweeping political and social reforms, Myanmar remains a deeply conservative nation.
But new fashions and overseas products are creeping into the once cloistered nation, supported by a proliferation of magazines for young consumers and an increasingly vibrant pop culture.
Last year a US-educated business graduate was selected as the first Miss Universe contestant to represent Myanmar in more than 50 years.
May Myat Noe is the latest in a growing list of beauty queens from Southeast Asia to run into trouble.
In June Thailand's contender for the Miss Universe pageant relinquished her crown after she allegedly called for supporters of the ousted government to be "executed", sparking a barrage of online criticism. - AFP