Some of Kenya's top athletes have threatened to stop representing their nation at international competitions like the Olympics over new tax laws.
Wesley Korir, an MP and former Boston marathon winner, said athletes would end up paying tax twice as they already pay tax on their winnings abroad.
Addressing a forum of athletes in Eldoret, he said athletes only pocket about 15% of their earnings.
The move could also see many athletes changing nationality, he said.
Kenya is home to some of the world's best middle- and long-distance runners.
The Kenya Revenue Authority (KRA) wants prize-winning athletes to pay the top rate of tax - 30% - on their earnings from this month.
But addressing the meeting at the University of Eldoret grounds in Kenya's Rift Valley, Mr Korir said the authorities should see the athletes as an asset.
"The breakdown for taxation and deductions is as follows: 30 to 35% for the country of origin, 15% for the agent, 10% for the manager, and now the KRA wants to add salt to injury by slapping a 30% tax of that amount," the Reuters news agency quoted him as saying.
"On behalf of the athletes, I say no - we say no taxation," he said to applause, a Kenyan TV report shows.
"When these athletes will stop going to the track to run, in the Olympics or the World Championships, that's when the importance of an athlete will be felt."
Other countries tended to reward their athletes - and these punitive measures could have long-reaching consequences, the MP said.
"Qatar pays Olympic medal in dollars… we are sounding the alarm that KRA may trigger a massive athletes' exodus," Kenya's Daily Nation newspaper quoted him as saying.
Florence Kiplagat, a two-time world champion, agreed, Reuters reports.
"If this matter goes on like this, I will defect to another country which will appreciate my effort," she said.
"We are taxed abroad. Then we invest our remaining earnings here although the government does nothing to support us. We work hard to give this nation a positive image abroad yet we get nothing in return."
Several high profile Kenyan runners have already switched their nationalities in recent years.
Tax has put other sports stars off running in some countries, like Jamaican sprinter Usain Bolt.
He only appears at events in the UK when the government gives a tax exemption, as the country not only taxes earnings, but also taxes a proportion of an athlete's global sponsorship income.