The parent body of athletics has launched a formal investigation into the matter "to ensure that the principle of fair play has been fully respected."
An IAAF spokesman, Giorgio Reineri, said that the case would be studied carefully, but that if the allegations were proved to be true, "in this case, it's obvious there is the disqualification of the athlete."
The incident comes at a time when the sport's image has been damaged by a succession of high-profile doping cases. It is a highly embarrassing situation for the IAAF in what is their flagship event for generating sponsorship and television revenue.
Barmasai's victory in Zurich has kept him in line for a share of the $1m (pounds 630,000) jackpot on offer to athletes who remain unbeaten through the seven-race Golden League series.
A spokesman for the Zurich meeting, Nicolas Russi, said: "There is no rule that one runner cannot speak to another during a race. We can't do anything."
But Wilson Kipketer, one of the three other athletes - along with the United States sprinter Marion Jones and the Romanian middle-distance runner Gabriela Szabo - also unbeaten with only two Golden League events remaining, expressed surprise at the behaviour of the 25-year-old world record holder.
"The jackpot is important but the main thing is to run the race," Kipketer said. "You can't get paid until you do the job."
During the race, Barmasai's fellow Kenyan Christopher Koskei was putting him under pressure over the final lap. But the 20-year-old appeared to ease off after a brief conversation, before speeding up again to draw close at the line.
After finishing in 8min 05.16sec, just 0.27sec ahead of Koskei, Barmasai explained to reporters: "Koskei's last 100 metres is really good. When he tried to pass, I tried to talk to him. I said: `Leave it for me'. That's why he slowed down.
"He would have won today but because he's a friend and we have to live together... the jackpot is for me and my friends."
Barmasai's artless confession fits into a Kenyan tradition of pragmatism when it comes to sharing out the sport's prizes.
Such has been Kenya's domination of the world cross-country championships over the last 10 years that they have effectively elected individual winners from within their teams. After the 1993 World Cross-country Championships in Spain, the Kenyan team manager said that William Sigei, who broke away from a group of team-mates to win, had been chosen to take the gold medal because he had shown he was the best runner at their training camps.
Four years ago, Kenya's Moses Kiptanui raised eyebrows in several quarters by slowing down as he won the world steeplechase title. He explained afterwards - with questionable candour - that he wanted to save beating the world record for a meeting after the championships where he would be paid for it. He duly won his bonus by becoming the first man to break eight minutes for the distance.
Perhaps the most controversial incident involving alleged on-track collusion between athletes occurred at the 1992 Barcelona Olympics - and on that occasion it was the Kenyan who lost out.
Richard Chelimo, who finished second behind Morocco's Khalid Skah in the 10,000m final, was temporarily awarded the gold medal after the Kenyans protested that Skah had received illegal help in pacing from a lapped Moroccan team-mate, Hammou Boutayeb.
But the title reverted to Skah the following morning after a successful Moroccan appeal.Reuse content