Ukraine says operation underway to retake south

STORY: The Ukrainian military said it launched a long-awaited counter-offensive to take back territory from Russian forces in its south on Monday, bolstered by weaponry supplied by the West.

Moscow acknowledged the offensive by Ukraine near the city of Kherson but also said it had failed, and that Ukrainians had suffered significant casualties.

Meanwhile, Russian shells bombarded the southern port city of Mykolaiv.

The city's mayor said homes had been hit and at least two people killed.

Reuters spoke to one man who barely survived, but lost his wife.

"I was in this room. I was in this half of the building. And I was watching the football review. It hit, and the wave went along the side of the house and it didn't destroy it. I was lucky."

This latest Ukrainian offensive comes after weeks of bloody stalemate in the war.

The conflict broke out when Russian troops poured over Ukraine’s borders in February, in what Russia calls a ‘special military operation' to rid Ukraine of nationalists and protect Russian-speaking communities.

Ukraine call it an unprovoked war of aggression.

Thousands have been killed, millions displaced, and the scale of fighting is larger than anything in Europe since World War Two.

Russia captured much of the south early on.

Now, Ukraine's using sophisticated Western-supplied weapons to hit Russian ammunition dumps, and wreak havoc with supply lines.

A spokesperson for Ukraine's southern command declined to give details of the counter-offensive, saying Russian forces in southern Ukraine remained "quite powerful."