Obasi, 33, who has been a free agent since leaving Swedish outfit AIK in January, made his last Super Eagles appearance in 2011 and had club spells in Germany with Hoffenheim and Schalke.
"I was supposed to be at the World Cup in 2014, I was playing with Schalke in the Champions League everything was going fine. At the end of the season, I was given an invitation for the World Cup preparations for friendlies in South Africa," Obasi said on social media.
"So, two days before the list came out, I was asked to pay some money if I wanted to be in the team," he added.
Obasi, who won a silver medal at the Beijing 2008 Olympics and played at the 2010 World Cup, said a move away from the Bundesliga fell through after missing the tournament four years later.
"I felt like I've paid my dues for the country, if you're a new player, I can get that but for me, it was a bit personal and very heart-breaking because I got injured – I was supposed to move from Hoffenheim to England," he said.
"And it takes a lot of dedication, it takes a lot of money and it takes a lot of investment in myself and my body. I went through surgery and did everything I could."
However, one of Nigeria's assistant coaches at the World Cup six years ago, Valere Houdonou, maintained Obasi was not good enough to make the final squad facing competition from the likes of Peter Odemwingie and Ahmed Musa.
"The question is, who could he have replaced among the strikers then?" Houdonou said.
"He was invited like every other potential player that could make the World Cup then because the coaching crew wanted to take the best to Brazil then.
"He failed to make the list because he could not displace anyone in the team," he added.
'Two-way thing'
Daniel Amokachi, who was also assistant coach at the World Cup in Brazil, took exception to Obasi's allegations particularly after head coach Stephen Keshi died in 2016, insisting the players are also guilty.
"This issue of bribe-taking or collecting in our football is not a one-way thing. Agents of players will come and meet a coach to offer money for their players to be taken," said the ex-Everton striker, who featured at the 1994 and 1998 World Cups.
"It's a two-way thing. Sometimes, players are the ones that will even go to the coach to say 'my agent said he will pay for me to be part of the team'," he said.
"You will also see some administrators and coaches who have turned agents that will try to be influencing things from the side," he added.
Nigeria's anti-corruption agencies are investigating senior officials of the Nigeria Football Federation (NFF) led by president Amaju Pinnick after "weighty" allegations were leveled against them.
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