MOSCOW, May 19 (Reuters) - The Russian branch of environmental group Greenpeace on Friday said it would shut down after authorities declared the group an "undesirable organisation", effectively banning it from operating.

In a statement, Russia's Prosecutor General said Greenpeace had tried to "interfere in the internal affairs of the state" and was "engaged in anti-Russian propaganda" by calling for sanctions against Moscow.

The label "undesirable" has been applied to dozens of foreign groups since Moscow began using the classification in 2015, and effectively bans an organisation outright.

"This decision makes it illegal for any Greenpeace activity to continue in Russia. Therefore, the Russian branch of Greenpeace is forced to close," Greenpeace Russia said in a statement posted on Telegram.

Later, Russia chief executive Sergei Tsyplenkov said he would take legal advice before deciding whether to appeal the ruling.

"I am not aware of any successful appeals against such a decision," he told Reuters in an interview. "We understood this could happen. But to say we were fully prepared for this would not be entirely honest."

Russia previously launched criminal proceedings against Greenpeace activists in 2013 when they attempted to scale an offshore oil rig in the Arctic Ocean belonging to state energy giant Gazprom, to protest against Arctic oil production.

In that incident, Russian security services boarded the group's Dutch-registered boat and took its 30 strong crew into custody, where they were investigated for piracy.

Born out of the anti-nuclear, counterculture movement of the late 1960s, Greenpeace is one of the largest and most recognisable environmental organisations in the world, operating in over 50 countries.

"I hope that environmental work is still allowed in our country," said Tsyplenkov. "I hope the state will not persecute our employees, me included."

Reporting by Reuters Editing by Andrew Osborn

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