Dmitry Peskov,Mr Putin's spokesman,told Russian Forbes magazine that"information about the birth of a baby fathered by Vladimir Putin does not correspond to reality". Miss Kabaeva,31,has been rumoured to be in a relationship with Mr Putin for several years,but the Kremlin has never acknowledged any link between the pair.
In 2008,a Russian tabloid newspaper was closed down by its owner after it ran a story on the rumoured relationship.
Mr Putin divorced Lyudmilla,his wife of 30 years,in 2013.
Friday's unconfirmed reports were the latest in a series of rumours to circulate since Mr Putin,62,cancelled a trip to Kazakhstan on Wednesday.