By Alexander Marrow and Andrew Osborn

LONDON, Dec 23 (Reuters) - WhatsApp complained about restrictions to its service in Russia on Tuesday, accusing the authorities of trying to deprive more than 100 million Russians of the right to private communications before the holiday season.

WhatsApp's statement followed a repeat warning by Russia's communications regulator that it would completely block WhatsApp if it did not comply with its demands to bring its services into line with Russian law.

"WhatsApp continues to violate Russian law. The messenger is used to organise and carry out terrorist acts on the territory of the country, to recruit their perpetrators and to commit fraud and other crimes against our citizens," Roskomnadzor, the regulator, told Russian state media.

It confirmed it was taking measures to gradually restrict WhatsApp as a result. Thousands of Russians complained about outages and slowdowns on Tuesday, monitoring websites showed.

"In restricting access to WhatsApp, the Russian government aims to take away the right to private, end-to-end encrypted communication from over 100 million people, right before the holiday season in Russia," a WhatsApp spokesperson said.

"WhatsApp is deeply embedded in the fabric of every community in the country – from parent and workplace groups to friends, neighborhood, and extended family chats across Russian regions. We’re committed to fighting for our users because forcing people onto less secure and government-mandated apps can only lead to less safety for Russian people."

RUSSIAN MOVES AGAINST FOREIGN-OWNED PLATFORMS

Russia in August began limiting some calls on WhatsApp, owned by Meta Platforms META.O, and on Telegram, accusing the foreign-owned platforms of refusing to share information with law enforcement in alleged fraud and terrorism cases.

Russian authorities, who also block or restrict social media platforms such as Snapchat, Facebook, Instagram and YouTube, are heavily pushing a state-backed messenger app called MAX, which critics say could be used to track users.

The authorities have dismissed those accusations as false and say MAX, which integrates various government-related services into it, is designed to simplify and improve the everyday lives of citizens.

(Reporting by Alexander Marrow and Andrew Osborn, Editing by Timothy Heritage)