A Russian prosecutor on Monday requested a sentence of three years and three months in a penal colony for a French researcher accused of breaching a "foreign agent" law.
The trial of Laurent Vinatier, who works for a Swiss conflict mediation NGO, comes amid tensions between Russia and the West over the Ukraine war.
The 48-year-old was arrested in Moscow in June and charged with collecting information on Russia's military without being registered as a "foreign agent", a crime punishable by up to five years in a penal colony.
A prosecutor told the judge that Vinatier should be found guilty.
The proposed sentence took into account that he "fully admitted guilt" and "repented for what he did" but said his actions posed "significant threats connected to Russia's security", the prosecutor said.
Vinatier's lawyer Oleg Bessonov said the proposed sentence was "extremely harsh".
"Our client committed a crime for the first time in Russia... and fully admitted his guilt," the lawyer said, asking the judge to fine him instead.
The "foreign agent" law, which entered force has been widely used to crack down on Kremlin critics but not usually foreign citizens.
French President Emmanuel Macron has demanded Vinatier's release, saying the "propaganda" against him "does not match reality".
In previous court hearings Vinatier had acknowledged violating the Russian law and apologised, explaining that he was unaware he should have registered as a "foreign agent".
Vinatier was charged over a requirement introduced in 2022 that people who collect information on Russia's military and arms that could harm country's national security, register as "foreign agents".
Russia has not charged or publicly accused Vinatier of espionage.
Tensions between Moscow and Paris are running high after France charged Russian-born Telegram founder Pavel Durov in August over illegal content on the popular social media platform, with the Kremlin warning against a "political persecution".
France has also strongly supported Ukraine in its fight against Russia's offensive and is training thousands of Ukrainian troops.
Vinatier is an adviser with the Geneva-based Centre for Humanitarian Dialogue, and is a veteran researcher on Russia and other post-Soviet countries.
The Centre "works to prevent and resolve armed conflicts around the world through mediation and discreet diplomacy", it says in a statement on its website.
'I love Russia'
"I always wanted to adequately present the interest and position of Russia on international relations in my work," Vinatier said at a hearing in July.
"I love Russia, my wife is Russian, my life is linked with Russia," he told the court.
Russia has arrested several Westerners and charged them with serious crimes during its Ukraine offensive, which ruptured ties with the West.
Washington has accused Moscow of arresting US citizens on baseless charges to use them as bargaining chips to secure the release of Russians convicted abroad.
On August 1, Russia freed US reporter Evan Gershkovich, former US Marine Paul Whelan and more than a dozen others -- including Russian opposition politicians -- in its biggest prisoner swap with the West since the Cold War.