BRUSSELS (Reuters) - Hungarian Prime Minister Viktor Orban on Thursday dismissed criticism that changes his government has made to the constitution are anti-democratic, saying there was no evidence of any contravention of European Union rules.

"Who is able to present even one single point of evidence, facts may I say, which could be the basis for any argument that what we are doing is against democracy? Just one concrete step," he told reporters ahead of a summit of EU leaders in Brussels.

"Without facts there is no sense of any general political discussion."

The European Union, the United States and human rights organizations have criticized the constitutional amendments, which they say limit the power of Hungary's top court, saying they could undermine democracy in the former Soviet satellite.

(Reporting by Luke Baker and Justyna Pawlak)