SEOUL (REUTERS) - Seoul City Amazones jumped to the defence of forward Park Eun Seon on Thursday after rival managers in the South Korean women's top flight threatened to boycott the league unless she takes a gender test.

Park, who played for South Korea at the 2003 women's World Cup and has won 19 caps, said she was "humiliated" by the incident while lawmakers have called for an investigation into whether her human rights had been violated.

The Korea Football Association said Park - who is 1.75m-tall and weighs 74kg - took and passed a gender test at the age of 15, though they did not reveal specifics of the result.

After news of the boycott threat emerged this week, the six coaches were the target of a social media backlash and tried to downplay the matter as a joke made at a private meeting.

Lee Sung Kyun, the coach of Suwon, said on Thursday he had resigned to apologise but maintained there was no real threat of a boycott and the issue of a gender test was merely to get Park back into the national team.

At a news conference held at Seoul City Hall, however, irate Amazones coach Seo Jung Ho lashed out at his rivals and said they were undermining Korean women's soccer.

"This should not have happened," he said, his voice rising with anger. "It is just so terrible to see the coaches, who should be mustering wisdom for the future of Korean women's soccer, colluding to hurt one of our best players."

Local media reported that six of the WK-League's seven coaches held an informal meeting on Oct. 19 and subsequently filed a complaint with the KFA that if Park did not take a gender test they would boycott next year's competition.

The 26-year-old, who played at the 2003 women's World Cup and won her last cap two years later, is the top scorer in the league this year with 19 goals.

"Excessive competition, selfishness and sexist insults (from the coaches) are plaguing this young player," continued Seo.

"She is older now and managing the situation in a more mature way than before. It looks like she is immune to it."

Park expressed incredulity on her Facebook site: "I can't believe this is happening again. I have gone through the gender examination thing several times. I did it in a World Cup, in an Olympics and in several others and there were no problems.

"I did it when I was young and I was mortified by them.

"I will try my best to make you feel dirty, just like I do," Park added in a comment apparently aimed at the coaches.