LVIV, March 21 (Reuters) - Ukraine on Monday (Mar 21) rejected Russian calls to surrender the port city of Mariupol, where residents are besieged with little food, water and power and fierce fighting shows little sign of easing.

"There can be no question of any surrender, laying down of arms," the Ukrainska Pravda news portal cited Ukraine's Deputy Prime Minister Iryna Vereshchuk as saying early on Monday.

"We have already informed the Russian side about this."

Russia earlier called on Ukrainian forces in Mariupol to lay down their arms, saying a "terrible humanitarian catastrophe" was unfolding.

It said defenders who did so were guaranteed safe passage out of the city and humanitarian corridors would be opened from 10am Moscow time on Monday.

Mariupol has suffered some of the heaviest bombardments since Russia invaded Ukraine on Feb 24. Many of its 400,000 residents remain trapped with little if any food, water and power.

Fighting continued inside the city on Sunday, regional governor Pavlo Kyrylenko said, without elaborating.

Vereshchuk said over 7,000 people were evacuated from Ukrainian cities through humanitarian corridors on Sunday, more than half from Mariupol. She said the government planned to send nearly 50 buses there on Monday for further evacuations.

Russia and Ukraine have made agreements throughout the war on humanitarian corridors to evacuate civilians, but have accused each other of frequent violations of those.

In his latest appeal for help from abroad, Ukrainian President Volodymyr Zelenskyy addressed the Israeli parliament by video link on Sunday and questioned Israel's reluctance to sell its Iron Dome missile defence system to Ukraine.

"Everybody knows that your missile defence systems are the best ... and that you can definitely help our people, save the lives of Ukrainians, of Ukrainian Jews," said Zelenskyy, who is of Jewish heritage.

Speaking in his daily video appeal to Ukrainians, Zelenskyy later welcomed the mediation efforts of Israeli Prime Minister Naftali Bennett, who has held numerous calls with him and Russian President Vladimir Putin.

"Mr. Bennett is trying to find a way of holding talks ... We are grateful for his efforts, so that sooner or later we will begin to have talks with Russia, possibly in Jerusalem," Zelenskyy said.

"That's the right place to find peace. If possible."

Mariupol's council said on Telegram that several thousand residents had been "deported" to Russia over the past week. Russian news agencies said buses had carried hundreds of refugees from Mariupol to Russia in recent days.

US ambassador to the United Nations Linda Thomas-Greenfield told CNN the deportation accounts were "disturbing" and "unconscionable" if true, but said Washington had not yet confirmed them.

Reuters could not independently verify the claims. Russia denies targeting civilians.

Greece's consul general in Mariupol, the last EU diplomat to evacuate the city, said it was joining the ranks of places known for having been destroyed in wars.

"What I saw, I hope no one will ever see," he said.