Park, the Beijing 2008 400 metres freestyle gold medallist, was only cleared to take part at Rio 2016 a month before the Games following a successful appeal against a Korean Olympic Committee ruling forbidding athletes from representing any national team for three years after a doping suspension.

The 27-year-old, one of South Korea’s household sporting names, was banned in 2014 after testing positive for the anabolic steroid testosterone and served an 18-month ban.

Speaking after the conclusion of the Asian Swimming Championships in Tokyo, where he won four gold medals, Park accused former Sports Minister Kim Chong - who stepped down last month due to his alleged involvement in the ongoing political scandal in South Korea - of blackmailing him to ensure he did not represent the country at the Olympics.

Park claims Kim attempted to force him into not participating at a meeting in May, according to the Yonhap news agency.

Representatives of the swimmer allege Kim offered to help Park gain sponsorship deals, while also making him a professor at the Dankook University in Seoul, if he gave up his attempt at being part of the South Korean team for Rio 2016.

His allegations remain unproven. 

"Back then, I was scared because he [Kim Chong] was in a high-ranking position," Park said.

"But I just wanted to go to the Olympics.

"There were talks about corporate sponsorships and college professorship, but it didn't really get through to me.

"Many thoughts went through my head and I felt the weight and responsibility.

"But what was important for me was to compete at the Olympics."

Following a tumultuous build-up to the Games in the Brazilian city, involving a protracted saga over whether he should be able to compete, Park struggled in the pool, failing to make it out of the heats in the 100m, 200m and 400m events.

He believes the alleged incident with Kim, coupled with the other difficulties he faced in the lead-up to Rio 2016, had an adverse effect on his performance.

"The Olympics is the stage where the best athletes in the world represent their respective countries and only focus on their competition," he said.

"I had to be in best form, but I had lots of things to think about other than swimming.

"I now regret that I wasn't mentally strong at the moment."

Park is now targeting success at next year’s World Championships in Budapest.

"If I can focus on my training and have a good working environment, I want to compete at the Tokyo Olympics [in 2020]," he said.

"Since many people are supporting me, I just want to put forth my best efforts."