American journalist David Satter kicked out of RussiaRussia has expelled American journalist and author David Satter, a former Moscow correspondent for the Financial Times and a longtime critic of Russian President Vladimir Putin, Satter told followers on Twitter.

Satter, the author of three books on Russia and the former Soviet Union, had been working as an adviser to the U.S. broadcasters Radio Free Europe and Radio Liberty since September.

"As some of you may know, I've been expelled from Russia," he wrote on his Twitter page Monday.

Satter told CNN he had gone to Kiev, the Ukrainian capital, to exchange his existing visa for a correspondent's visa when he was told his application had been rejected, on the grounds that his presence in Russia was "undesirable." He is now in London "until we figure out what to do next."

Satter is a fellow at Johns Hopkins University and the Hudson Institute, a U.S.-based think tank. He has written extensively on the history of Russia in the post-Soviet era.

In a prepared statement, the Russian Foreign Ministry accused Satter of violating entry visa regulations.

It said that after entering Russia on November 21, he waited five days before converting his initial visa into a multi-entry visa -- a "major breach of the Russian migration law."

After receiving his accreditation from the ministry, Satter was supposed to immediately go to the Federal Migration Service to get his multientry visa, but he showed up there on November 26, the statement said.

Satter spent about five days in Russia "illegally" in November, according to the ministry.

A Moscow court heard his case on November 29, and he was fined and ordered to leave the country, the ministry said. Satter left Russia on December 4.

He is now barred from the country for five years, the ministry said, adding that this was not uncommon, with more than 500,000 foreign citizens banned from entering Russia for three to 10 years because of breaking rules.

In December, after suicide bombers killed more than 30 people in the Russian city of Volgograd, Satter wrote for CNN.com that visitors to the upcoming and highly touted Winter Olympics in the Black Sea city of Sochi "are walking into what effectively is a war zone." But he said he didn't know what prompted the government to kick him out now.

"I've always been critical of the Putin regime. This is nothing new," he said. "It may be that for reasons of their own, they've finally found that criticism to be more than they wanted to put up with. But there's actually quite a lot to criticize, so if you're going to report honestly from Russia, you almost have to be critical."

Satter said the language used to reject his visa hearkened back to the Cold War era and its application to a journalist was "unprecedented." But whether it reflected a shift in policy toward international newsgathering was unclear, he said.

"In any case, the expulsion of even one correspondent has an effect on everybody else because it makes it clear that critical reporting may incur a very serious cost," he said.