Just in: Russia-Ukraine ceasefire talks begin at Belarus border

• Over 500,000 refugees have fled Ukraine, says UN

Ceasefire talks between Russian and Ukrainian officials began on the Belarusian border on Monday as Russia faced deepening economic isolation four days after invading Ukraine.

Russian forces seized two small cities in southeastern Ukraine and the area around a nuclear power plant, the Interfax news agency said.

But they ran into stiff resistance elsewhere as the biggest assault on a European state since World War Two failed to make as much ground as some had expected.

Reuters reports that talks began on Monday with the aim of an immediate ceasefire and the withdrawal of Russian forces, the Ukrainian president’s office said. Russia has been cagier about the talks, with the Kremlin declining to comment on Moscow’s aim.

It was not clear whether any progress could be achieved after Russian President Vladimir Putin put Russia’s nuclear-armed units on high alert on Sunday.

The talks are being held on the border with strong Russian ally Belarus, which has become a launch pad for the invading Russian troops. read more

“Dear friends, the President of Belarus has asked me to welcome you & facilitate your work as much as possible. As it was agreed with the Presidents (Volodymyr) Zelenskiy and Putin, you can feel completely secure,” Belarusian Foreign Minister Vladimir Makei said at the start, according to the foreign ministry’s translation on Twitter.

The Western-led response to the invasion has been emphatic, with sanctions that effectively cut off Moscow’s major financial institutions from Western markets. Russia’s rouble currency plunged 30% against the dollar on Monday. Countries also stepped up weapons supplies to Ukraine.

Blasts were heard before dawn on Monday in the capital Kyiv and in the northeastern city of Kharkiv, Ukrainian authorities said. But Russian ground forces’ attempts to capture major urban centres had been repelled, they added.

The Ukrainian General Staff said Russian forces were focusing on Chernihiv city, northeast of Kyiv, and parts of Donetsk region in the east among other areas.

Kyiv authorities warned residents emerging from a weekend curfew that they would see newly erected fortifications, tank traps and other defensive installations in the streets as the city girds for further battle.

Russia’s defence ministry said its forces had taken over the towns of Berdyansk and Enerhodar in Ukraine’s southeastern Zaporizhzhya region as well as the area around the Zaporizhzhya nuclear power plant, Interfax reported. The plant’s operations continued normally, it said.

Ukraine denied that the nuclear plant had fallen into Russian hands, according to the news agency.

Dozens of people were killed in Russian rocket strikes on Kharkiv on Monday, Ukrainian interior ministry adviser Anton Herashchenko said.

UN human rights chief Michelle Bachelet said at least 102 civilians in Ukraine have been killed since Thursday, with a further 304 wounded, but the real figure is feared to be “considerably higher”. read more

More than half a million people have fled to neighbouring countries, according to the United Nations refugee agency.

Fighting took place around the Ukrainian port city of Mariupol throughout the night, Pavlo Kyrylenko, head of the Donetsk regional administration, said. He did not say whether Russian forces had gained or lost ground, or provide any casualty figures.