Opponents of Prime Minister Viktor Orban are using referee whistles to disturb the government's commemorations of Hungary's 1956 revolution.

Opposition politicians say Orban's policies, like his deal for Russia to build new reactors at Hungary's only nuclear power plant, go against the spirit of the brief, but bloody anti-Soviet uprising.

The Egyutt (Together) opposition party distributed whistles for its supporters to sound at the memorial event outside the Hungarian Parliament on Sunday along with symbolic red cards.

Peter Juhasz, the party's vice president, says "Orban's policies are exactly the kind which Hungarians rebelled against in 1956."

Orban's critics accuse him of weakening Hungary's system of democratic checks and balances.

Polish President Andrzej Duda also is scheduled to speak at the commemoration.