Mike Tyson\'s signing of a US teen amateur boxing star to a professional contract has sparked verbal jabs from USA Boxing president Charles Butler after losing a top Olympic prospect. Former world heavyweight champion Tyson, now a fight promoter, signed Erickson Lubin on Tuesday, the young prospect\'s 18th birthday, according to a Twitter posting by the fighter, who said, \'My pro career starts now.\" Butler wrote an open letter to Tyson asking him to stop trying to lure Olympic prospects into the pro ranks. \"You are offering these athletes pennies on the dollar of what they could be worth with an Olympic medal or even potentially just being an Olympian,\" Butler wrote to Tyson. \"You are also undermining the next United States Olympic boxing team in the process.\" USA Boxing said it will seek action from lawmakers to stop \"professional promoters from attempting to sign athletes in the Olympic pipeline.\" No US boxers won Olympic medals at London last year and the lone medal from 2008 at Beijing was a bronze by Deontay Wilder. Not since reigning super-middleweight world champion Andre Ward won Athens gold in 2004 has a US male fighter collected gold. Lubin had been offered a residency training program spot at the US Olympic training center in Colorado, all at no cost, whereas his pro training figures to be financed by future fight income. Source: AFP