The Russian interior ministry said in a statement Cuban officials had informed Interpol of the arrest of Maxim Martsinkevich, RIA Novosti reported.
A Russian court arrested Martsinkevich last month in absentia on hate charges.
Martsinkevich blamed what he called Russia's "pedo-lobby" for the charges and left Russia Jan. 8, saying he would not return. The next day he posted on his website he had flown to Cuba from Ukraine.
Martsinkevich, better known by his nickname "Tesak," or machete, was released from prison in 2010 after serving a 3 1/2-year sentence for incitement to hatred.
In 2011, he founded Occupy Pedophile, a vigilante group that used false promises of sex with minors to lure men to meetings where the men were then assaulted.
The group also reportedly targeted gay men.