MOSCOW (Reuters) - Russian nationalists threatened on Tuesday "to cure" any homosexuals who join a Gay Pride parade in Moscow this Saturday, setting the scene for a possible confrontation on the day of the Eurovision Song Contest final.

The Moscow authorities say they cannot allow the parade to take place as it will "destroy morals" in the capital. But gay activists said they have so far received no formal denial of their request for the parade.

"We will cure them for sure. We will help them to the hospital to be treated by the doctors. They are ill people," Alexei Samsonov, a right-wing activist, told Reuters.

"The authorities cannot allow this disgrace to take place. There can be no gay parade in Moscow," he said, adding that he and fellow activists would come out on the streets on Saturday to show their opposition to the parade.

Many nationalists and extreme Russian Orthodox believers say homosexuality is an evil which needs to be stamped out to prevent it ruining Russia.

Gay activists in Russia say they are fighting for their constitutional rights in a deeply intolerant society and compare their plight to that of gays in Western Europe at the beginning of the last century.

They say they will hold the Gay Pride parade even if Moscow does ban it.

Russia decriminalized homosexuality in 1993 but tolerance is not widespread. At an unsanctioned Gay Pride parade in 2007, nationalists shouting "death to homosexuals" punched and kicked gay demonstrators.

(Reporting by Guy Faulconbridge, editing by Paul Casciato)