This is CNBC's live blog tracking developments on the war in Ukraine.  

The funeral of Russian opposition leader Alexei Navalny is scheduled to take place in Moscow on Friday, with large numbers expected to attend despite heightened political tensions and fears of arrests.

Images on Thursday showed barriers being erected around the church where a memorial service will be held at 2 p.m. local time, and the cemetery where the burial is due to take place at 4 p.m. Mourners began to gather Friday morning.

The cause of Navalny's death in an Arctic penal colony on Feb. 16 remains unexplained, but reports say his death certificate states "natural causes." The longtime critic of Russian President Vladimir Putin was serving a 19-year jail term on charges of extremism.

Navalny's supporters, his widow Yulia Navalnaya, and world leaders including U.S. President Joe Biden have accused Putin of being "responsible" for his death. The Kremlin denies involvement and has slammed any suggestion of it.

Navalny's spokesperson Kira Yarmysh on Thursday urged those in Moscow to attend the event, which is set to be livestreamed on YouTube. Memorial services have been scheduled in other Russian towns and cities for Friday evening.

According to Yarmysh, several funeral agencies, commercial venues and funeral halls refused to host the service. Yarmysh said on social media platform X that "unknown people" had been calling hearse operators to "threaten them" not to transport Navalny's body.

Navalnaya, who is overseas, told European parliamentarians earlier this week she did not know whether the funeral would be peaceful or whether there would be arrests. A heavy policy presence is expected.

Mourners seen arriving for Navalny funeral

Images on Friday morning showed mourners beginning to arrive at a Moscow church in the Maryino district ahead of the memorial service for Russian opposition leader Alexei Navalny, which will be held at 2 p.m. local time.

Navalny's supporters have urged people to attend and said they expect crowds, but warned they do not know whether there will be arrests amid high political tensions.

— Jenni Reid

Newspaper says its editor was detained for 'discrediting' Russian army

Sergey Sokolov, editor-in-chief of Novaya Gazeta, an independent newspaper that has been banned in Russia, was detained in Moscow, the paper said.

He is being accused of "discrediting" the Russian army in an article for the paper, it said, however it is unclear which article exactly.

Novaya Gazeta was blocked in Russia in 2022 and lost its media license in 2023. Most of its journalists have been reporting from outside of Russia since shortly after the war began.

Previous Editor-in-Chief Dmitry Muratov, who won the Nobel Peace Prize in 2021, stepped down last year after being deemed a "foreign agent" by Russian authorities. This label is commonly given to Kremlin critics and imposes rules and restrictions on them.

— Sophie Kiderlin

Over 500 people suspected of war crimes, 81 convicted, Ukraine says

Over 500 people have been suspected of war crimes since Russia's war with Ukraine began, and 81 have been convicted, Ukraine's Prosecutor General Andriy Kostin said Thursday during a war crimes conference in Kyiv, Reuters reported.

On the sidelines of the conference, a two-year extension of a joint investigation team, which brings together chief prosecutors from various European countries, Europol and the Office of the Prosecutor of the International Criminal Court, was announced by EU justice arm Eurojust.

The group focuses on alleged international crimes in Ukraine, including investigations and prosecutions. The investigations have led to Lithuania announcing suspicions of a war crime against a civilian citizen, who was allegedly tortured and killed while in Ukraine in 2022, Kostin said on social media platform X.

— Sophie Kiderlin

From babies to boosting troops: Putin's speech covers variety of topics

Russian President Vladimir Putin's State of Nation address Thursday has covered a variety of topics so far, from Russia's low birth rate, to the risk of an arms race with the United States, to low incomes and improving relations with the Middle East and Latin America.

Putin proposed to increase child benefits and improve social services to support and encourage Russians to have large families, as well as efforts to increase low incomes and Russian life expectancy.

He also spoke of Russia's need to strengthen its western military district, signaling an intention to boost troop numbers along the border with new NATO member Finland. Putin said Russia's armed forces had gained a wealth of military experience from fighting in Ukraine, stating "the combat capabilities of the armed forces have increased manifold."

"Our units are firmly in possession of the initiative. They are confidently advancing in a number of operational directions, liberating new territories," he told the audience, made up of lawmakers, officials, religious leaders and journalists.

— Holly Ellyatt

Read CNBC's previous live coverage here:

'I bow deeply to you,' Putin tells Russian troops; Ukraine says it has shot down more warplanes