NOVOSIBIRSK, Russia -- The first trip outside Moscow in three years for Alexei Navalny highlights the challenges faced by Russia's beleaguered opposition.

The 39-year-old anti-corruption campaigner and sharp-tongued Kremlin critic on Sunday attracted only a few hundred supporters to a rally in Russia's third-largest city to urge voters to participate in primaries that will choose opposition candidates for regional elections.

And the rally also attracted dozens of rowdy protesters who shouted abuse and accused Navalny of being a U.S. spy. Earlier, several people threw eggs at him as he was on his way to the gathering.

Navalny didn't back off from the animosity and during the rally he even invited one of the protesters to come up on stage and air his views. The man blamed corruption and Russia's other problems on the United States, contending that the fact that many areas in the Novosibirsk region have no hot water is a "consequence of the Soviet Union's loss in the Cold War against the United States."

Navalny told the rally "I'm here to convince you to put your trust in democracy."

The primaries are to be held June 14-15 to pick candidates for the September regional elections. The elections are to be held in 16 regions, but the opposition is aiming to field candidates only in three regions.

The decision reflects how opposition forces are weak in much of the country and that the domination of Kremlin-appointed governors in some regions entails the risk of physical threats. The United Russia party that obediently backs President Vladimir Putin's every initiative has a smothering domination of national politics and opposition figures get barely any coverage from state-controlled television.

But Navalny sees Novosibirsk, a scientific centre where education levels are comparatively high, as a potential foothold.

"Here, in Novosibirsk people are ready for it," Navalny said. "I'm convinced that when this happens and in all regions opposition candidates will be nominated by people, then we will make it to the parliament, we finally will receive political representation."

Navalny had not left Moscow since 2012 because of trials for corruption charges, but a court earlier this year lifted his house-arrest restriction. Although convicted in both cases, he avoided prison. His brother was sent to prison in one of the cases.

Navalny was the driving power behind anti-Putin protests in 2011-12 and his investigation into official corruption has exposed the wealth of Russian officials.