Russian police on Thursday detained top opposition leader Alexei Navalny as they conducted fresh searches at his Moscow-based anti-corruption foundation, a spokeswoman said.

"Alexei has been forcibly detained and led away," his spokeswoman Kira Yarmysh said on Twitter.

"He did not put up resistance," she said, adding that searches at the FBK anti-corruption foundation were currently under way.

Yarmysh suggested that the authorities chose to raid the offices on Thursday because Navalny was scheduled to address supporters in a weekly YouTube programme in the evening.

Navalny's staff released a video showing how law enforcement agents tried to break into the FBK offices using a saw, with sparks flying around.

"New Year's fireworks," Navalny's ally Nikolai Lyaskin quipped on Twitter. Another video showed men clad in black uniforms and sporting masks and helmets serching the FBK office premises.

In a separate development, Russia's top opposition newspaper Novaya Gazeta said Thursday that authorities had searched the Moscow apartment of its special correspondent Yulia Polukhina.

After the raid, the mother of two children had been taken away to "an unknown destination," the newspaper said in a statement.

The 43-year-old Navalny helped organise major protests against the government this summer
The 43-year-old Navalny helped organise major protests against the government this summer AFP / Yuri KADOBNOV

"So far this looks like an abduction," Novaya Gazeta said.

It added that the searches were linked to Novaya Gazeta publications including those concerning "illegal armed groups" operating in the war-torn eastern Ukraine where Kiev is battling against pro-Kremlin separatists.

Authorities have been steadily ramping up pressure on Navalny and his allies in recent years with regular searches and short jail terms for President Vladimir Putin's top opponent and his allies.

The 43-year-old Navalny helped organise major protests against the government this summer when tens of thousands took to the streets of Moscow to demand fair elections.

A number of people received jail terms for taking part in those protests.

On Wednesday Navalny said that one of his allies had been forcibly conscripted and sent to serve at a remote Arctic base, in a move his supporters also said amounted to kidnapping.

Ruslan Shaveddinov, a project manager at Navalny's FBK foundation, went missing Monday after police broke into his Moscow flat and his phone's SIM card was disabled.

He resurfaced Tuesday at a secret air defence base on the remote Novaya Zemlya archipelago in the Arctic Ocean.

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