Ukraine: The mayor of Ukraine's Mariupol said on Tuesday (Mar 1) morning that the southern port city was under constant shelling which had killed civilians and damaged infrastructure, as Russia started day six of its invasion.

"We have had residential quarters shelled for five days. They are pounding us with artillery, they are shelling us with GRADS, they are hitting us with air forces," Vadym Boichenko said in a live broadcast on Ukrainian TV. "We have civilian infrastructure damaged - schools, houses. There are many injured.

There are women, children killed," he said. Ukraine's largest steelmaker Metinvest BV has most of its facilities located in Mariupol where it has halted production. The company sent most workers home while reduced shifts ensured the equipment was not breaking down.

Meanwhile, the city has been left without electricity following attacks from advancing Russian forces, the head of the region Pavlo Kyrylenko said on Tuesday. "Mariupol and Volnovakha are ours!" Kyrylenko wrote on Facebook. "The two cities are under pressure from the enemy but they are holding on. In Mariupol, electricity lines have been cut and the city is without power."

Both cities lie between territory held by Russian-backed separatists and the Crimean peninsula annexed by Moscow in 2014, and Russian forces have been working to join the two regions. Mariupol, an important port city of between 400,000 to 500,000 people, has been under attack since Moscow launched its invasion of Ukraine last week. Volnovakha has a population of around 20,000.

Mariupol was briefly occupied by pro-Moscow separatists when fighting broke out with the Ukrainian army in 2014, following historic street demonstrations that ousted a pro-Kremlin president. Ukraine's second-largest city of Kharkiv also came under heavy attack, the regional administration head said on Tuesday,

while an adviser to the country's president said Russia was deliberately shelling cities to spread panic among Ukrainians. Russia calls its actions in Ukraine a "special operation" that it says is not designed to occupy territory but to destroy its southern neighbour's military capabilities and capture what it regards as dangerous nationalists.