Here are the latest developments in the war in Ukraine:

Ukrainian President Volodymyr Zelensky urges citizens around the world to take to the streets to stop Russia's invasion of his country.

"Come with Ukrainian symbols to support Ukraine, to support freedom, to support life," Zelensky says in a video address in English. "Come to your squares, to your streets, make yourselves visible and heard."

Russia's foreign ministry says it is expelling US diplomats in retaliation for Washington's step to remove 12 of Moscow's representatives at the United Nations in New York.

"The US side has been given firm notice that any hostile action by the United States against Russia will be met with a resolute and appropriate response," the ministry says in a statement.

The Russian army has retreated more than 30 kilometres (18 miles) east of Kyiv and has begun to establish defensive positions on several fronts in Ukraine, a senior Pentagon official says.

To the northwest, "they're basically digging in and they are establishing defensive positions," the official adds. "So it's not that they're not advancing. They're actually not trying to advance right now."

As US President Joe Biden arrives in Brussels, warning of a "real threat" Russia may use chemical weapons, a top US official says new sanctions are coming against Russian "political figures" and wealthy elites close to President Vladimir Putin.

"We, the United States, will announce a package of sanctions designations tomorrow that relate both to political figures, (and) oligarchs... as well as entities," National Security Advisor Jake Sullivan tells reporters aboard Air Force One as Biden heads for NATO and EU summits on Ukraine.

Zelensky says almost 100,000 people are still trapped in the ruins of Mariupol, after more than 7,000 escaped on Tuesday.

Human Rights Watch describes the southern port city as a "freezing hellscape riddled with dead bodies and destroyed buildings".

The United States has reached the assessment that Russian military forces have committed war crimes in Ukraine, US Secretary of State Antony Blinken announces.

NATO chief Jens Stoltenberg tells an emergency Brussels summit allies will sign off on sending four "battle groups" to eastern members Bulgaria, Hungary, Romania and Slovakia.

He also signals cybersecurity assistance as well as equipment "to help Ukraine protect against chemical, biological, radiological and nuclear threats".

A Maxar satellite image taken on March 2 shows buildings on fire in the city of Mariupol, where nearly 100,000 people remain trapped
A Maxar satellite image taken on March 2 shows buildings on fire in the city of Mariupol, where nearly 100,000 people remain trapped Satellite image ©2022 Maxar Technologies via AFP

Germany says it is sending 2,000 additional anti-tank weapons to Ukraine to help it repel the Russian invasion, a parliamentary source tells AFP, confirming media reports.

The Ukrainian forces have already received 1,000 anti-tank weapons and 500 Stinger-type surface-to-air missile launchers from the Bundeswehr, the German army.

Prime Minister Boris Johnson says Britain will send 6,000 missiles and ?25 million ($33 million, 30 million euros) in financial aid to Ukraine's army to help it fight Russian forces.

The announcement of the funding and additional military hardware, consisting of anti-tank and high explosive weapons, comes on the eve of NATO and G7 summits set to discuss the Russian invasion.

French car giant Renault announces it is immediately suspending operations at its Moscow factory after Kyiv calls for a boycott of the company for remaining in Russia.

Renault is also considering "the possible options" for its Russian affiliate AvtoVAZ, the company says in a statement.

A Russian journalist for investigative news outlet The Insider is killed when Russian troops shell a residential neighbourhood in the Ukrainian capital, the outlet says, the latest reporter to die in the war.

German Chancellor Olaf Scholz says "Putin's offensive is stuck" and urges Moscow to "immediately" stop the fighting, saying it is not only destroying Ukraine but "Russia's future".

The Pentagon says it believes as much as 10 percent of Russian forces committed to Ukraine may have been knocked out in just four weeks of fighting and that Russian forces "have struggled with logistics and sustainment".

Russia's ally Belarus says it is to expel most Ukrainian diplomats, accusing Kyiv of "interference" in its domestic affairs, leaving just five people from a 20-strong team at its embassy in Minsk.

Poland says it has expelled 45 Russian diplomats for espionage, an allegation dismissed as baseless by Russia's ambassador to Poland.

The EU gives member states the nod to offer limited subsidies and cheap loans to companies impacted by the war in Ukraine or sanctions imposed on Russia.

More than 3.6 million Ukrainians have now fled the country following Russia's invasion, the United Nations says. More than 10 million have been displaced from their homes.