Increasingly isolated by the West, Vladimir Putin will hope to find a friendly ear in Pope Francis at their meeting Wednesday, but experts say the Russian President may have misjudged the mood.

The conflicts in the Ukraine and Syria are likely to dominate the talks, organized on the sidelines of a visit to Milan 2015 expo's Russian pavilion.

Russian President Vladimir Putin on Thursday banned revealing information about troop deaths in "special operations" during peacetime, as the Kremlin continues to rebuff accusations its soldiers are fighting in Ukraine. 

The strongman signed an amendment adding to what Russia classifies as "state secrets" any "information revealing losses of personnel... in peacetime during special operations." 

U.S. Vice President Joe Biden on Wednesday denounced Vladimir Putin's "pure aggression" in Ukraine, warning that Western nations must be prepared to respond with further sanctions against Russia if necessary.

Condemning the Russian president's actions abroad and repression at home, Biden said facing down Putin was "critical to checking further aggression down the road."

Britain's David Cameron and Russia's Vladimir Putin have agreed to re-start talks on finding a solution to the crisis in Syria, a statement from Cameron said on Monday.

The Russian president phoned Cameron to congratulate him on his re-election as prime minister and the two agreed that Syria talks should resume, a spokeswoman from Cameron's office said.

The United States led criticism of Russia's new law targeting "undesirable" NGOs, which activists fear will stifle critical voices at international rights groups working in the country.

Under the law signed by President Vladimir Putin on Saturday evening, Russian prosecutors will be able to target foreign groups whose "undesirable activities" are deemed to threaten "state security" or the "basic values of the Russian state."

Iraqi Prime Minister Haider al-Abadi on Thursday urged the Russian leadership to boost its involvement in the fight against the Islamic State group, with Moscow pledging to supply weapons.

On a visit to Moscow, Abadi warned Russian President Vladimir Putin and Prime Minister Dmitry Medvedev that terrorism is spreading, days after IS fighters seized the strategic Iraqi city of Ramadi, dealing a major blow to the government.

A Moscow court on Wednesday ruled against jailing leading opposition politician Alexei Navalny after the prison authorities asked for his suspended sentence to be turned into a custodial term.

A nail-biting hearing in southern Moscow saw Navalny, a charismatic protest leader and one of President Vladimir Putin's biggest critics, arrive at the courtroom with a large bag of his belongings packed to take to a penal colony.

U.S. Secretary of State John Kerry on Wednesday warned Russia that now was a critical time to implement a fragile peace deal to end the fighting in Ukraine, after his talks with President Vladimir Putin raised hopes of a slackening in tensions.

Kerry said there was an "enormous moment of opportunity" to bring to an end over a year of fighting in eastern Ukraine between government forces and pro-Russia separatists which has dragged relations between Moscow and the West to a new post-Cold War low.

Russia vowed Tuesday it was ready to work with the United States on a host of burning issues but insisted it would not bow to "coercion," as President Vladimir Putin hosted top U.S. diplomat John Kerry. 

On the highest-level U.S. visit to Russia since the conflict in Ukraine erupted in late 2013, Putin met with Kerry at his summer residence in the Black Sea resort of Sochi.

Al-Mustaqbal movement leader ex-PM Saad Hariri arrived Tuesday evening in the Russian capital Moscow on an official visit.

Hariri will meet with Russian President Vladimir Putin, Foreign Minister Sergei Lavrov and a number of officials during his stay, his press office said.