Nwankwo Kanu's official age is 33 but his real age is 42. Obafemi Martins is not 25 but 32. Jay-Jay Okocha was 10 years older than his "official" age throughout his career. And Taribo West, whose playing career ended only two years ago, is in his late fifties. Who says so? A stream of bloggers on some of Nigeria's most popular websites, in response to comments made after the country's timid effort in last month's Africa Cup of Nations.

Failure to win that trophy is nearly always considered a scandal in the continent's most populous nation but Nigeria's latest misadventure in the tournament triggered a particularly explosive condemnation back home.

It started when a former manager of a leading Nigerian club told the Lagos Guardian: "What happened in Angola is a confirmation of what has been happening in the past where most of our players falsified their age during competition. Most of the players are beyond the age they professed and this made it impossible for them to withstand the pace of teams like Zambia and Benin."

It also led to an entertaining discussion that shows no sign of abating as the Nigerians, who have three months to prepare for the World Cup, reacted to the criticism by sacking the coach. "Our boys are old, we are paying the price for age cheating," said Ken Anugweje, a former national team doctor and board member of the Nigerian Football Federation.

Suspicions about true ages of some Nigerian footballers date back 20 years. Fifa banned Nigeria from all international fixtures for two years after finding that the birth dates of three of their players in the 1988 Olympics were different from ones used by the same players in previous tournaments.

A year later Pelé famously declared "an African team will definitely win the World Cup by the turn of the century" after watching seemingly promising Nigerian youngsters lift the Under-17 World Cup and reach the final of the Under-20 competition. How was Pelé to know that the so-called Under-20s of 1989 were so old that, in the words of George Onmonya on nigeriavillagesquare.com, "most of our players have now retired and become grandpas"?

Nigeria have a rich tradition of seemingly promising youngsters who mysteriously fail to fulfil their potential. Phillip Osondu was the best player at the 1987 Under-17 World Cup, after which he was snapped up by Anderlecht, only to drift out of the game and into janitorial work after questions were raised about his real age.

The star of Nigeria's finalists at the 2001 Under-17 competition went on to become officially the third-youngest player to appear in the senior World Cup when he started the 0-0 draw with England in 2002. But that was as good as it got for Femi Opabunmi, who by 2005 was playing part-time football in the French lower leagues.

A trawl through the blogosphere makes for intriguing reading. "A friend of mine who once played in the Nigerian league told me his real age was 34 but his football age was 21," wrote Onmonya. "You can walk into any immigration office in Nigeria today, forge documents at the nearby business centre, change your name, place of birth, date of birth, pay 7,000-10,000 naira instead of the official price of about 5,500 for an international passport and within hours you have completed the whole process." A new passport, a new person – and if you are a footballer, a younger one.

A former employee of the British embassy in Nigeria told Observer Sport that when visa applicants complained to him about having their applications rejected, he would reply: "Well don't talk to me about it, I'm dead." He would respond to their looks of puzzlement by pointing to the wall behind him, on which hung his death certificate, purchased for a small fee from a Lagos supplier. Fifa reckon they have finally come up with a foolproof way of determining real age. Ahead of last year's Under-17 World Cup in, as it happened, Nigeria, the governing body announced that players would be subjected to wrist scans using magnetic resonance imaging, and this would determine their true age.

That led some countries to undertake precautionary scans beforehand. The results were never announced, but Nigeria suddenly discarded 15 squad members, while Gambia omitted 11 of the 18 who had helped them to victory in the African Under-17 championship a few months earlier. Reports claim that retrospective analyses of the previous three Under-17 World Cups showed more than a third of all players were too old.