MOSCOW - The Russian Foreign Ministry, in its first statement about an expelled British newspaper correspondent, said Tuesday evening that he could return to Russia if he complies with accreditation rules.

The Guardian correspondent, Luke Harding, who had written a number of articles about high-level corruption and other sensitive issues, was put in an airport cell and then on a plane back to London after returning Saturday from a two-month absence with a valid visa.

The Foreign Ministry said that although Harding received a visa extension through May in November, he left the country "for London for his own business without receiving a foreign correspondent press card issued in his name." It said he could work in Russia until his visa expires if he resolves the accreditation issues, according to the Interfax news agency.

Earlier in the day, the Glasnost Defense Foundation, which documents the murders, beatings and harassment of journalists in Russia, suggested the expulsion was meant to send a warning.

"It is a ritual of political pressure carried out by our most mighty secret services," said Alexei Simonov, president of the foundation. "It shows all others they are under surveillance and if they think of themselves as being free, the secret services are showing them their place. It is a sign for you and Russian journalists as well."

Harding, the Guardian's Moscow correspondent since 2007, had recently reported on WikiLeaks cables, which included descriptions of pervasive government corruption in Russia.

In December, two opposition politicians referred to a Harding article in court as part of their defense in a defamation case. The politicians, Boris Nemtsov and Vladimir Milov, had asserted that a profitable oil trading business run by a Putin acquaintance was actually benefiting Putin. The acquaintance sued and won last week, but the two plan to appeal.

"The Guardian was one of the first to write about this company in December 2007," Milov said Tuesday. "We met with Luke Harding, and he shared his thoughts on the investigation. We mentioned his article in court to show there's a wide perception in the press that Putin benefited."

Milov suggests that might have gotten Harding in trouble. "We'll never know," he said. "You can only guess."

In 2008, a British freelancer, Simon Pirani, was turned away even though he arrived with a valid visa. He had been in Russia earlier interviewing for a book about civil rights.

In 2007, a Moldovan citizen who was working for a Russian newsweekly, the New Times, was refused reentry when she returned from a trip out of the country. She had been investigating money laundering schemes connected to government officials.

And in 2006, British journalist Thomas de Waal was refused a visa when he wanted to visit to promote his book about the Nagorno-Karabakh conflict. Earlier he had reported extensively from Russia, especially on the fighting in Chechnya.