Mobile communications were severed Friday in Saint Petersburg in "unprecedented" security measures as President Vladimir Putin attended a global economic forum amid growing Ukrainian attacks on Russian soil.
The Roskongress Foundation, the organisers of the forum in Russia's second city, earlier said internet communication via mobile operators would be blocked.
"Use wifi", said Kremlin spokesman Dmitry Peskov, linking the heightened security to the threat of attacks from Ukraine.
In the buildings hosting the forum, sniffer dogs were on patrol and long queues of vehicles waited to be searched, according to the local Fontanka daily.
"The security measures... are unprecedented", Peskov was quoted as saying by the Interfax news agency.
"This is normal practice. The enemy acts brazenly and does not abandon its attempts to cause damage", said Peskov, adding that in such conditions "it is very important to remain attentive and mobilised".
The forum in takes place in western Russia at a time when the country has been the target of numerous drone attacks in recent weeks, along with an armed incursion and explosions blamed by Moscow on Kiev's forces.
Saint Petersburg is far from Ukraine, but an influential paramilitary blogger, Vladlen Tatarsky, was killed in an explosion here in April.
Moscow accused Kyiv's secret services and Russian opponents of masterminding the attack.
A few weeks later, a high-voltage power line was damaged by another explosion near St Petersburg, with the Russian authorities suggesting sabotage.
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© Agence France-Presse
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