The United States will back Ukraine until its security is "guaranteed", US Secretary of State Antony Blinken said on a trip to Kyiv yesterday, hours after Russian forces claimed further advances in the northeastern Kharkiv region.

Blinken's visit comes just weeks after the US Congress finally approved a $61bn financial aid package for Ukraine following months of political wrangling, unlocking much-needed arms for the country's outgunned troops.

"We're with you today. And we will stay by your side, until Ukraine's security, sovereignty, and ability to choose its own path is guaranteed," Blinken said in a speech.

"The assistance is now on its way. Some of it has already arrived. More will be arriving," he had told Ukrainian President Volodymyr Zelensky during a meeting earlier.

"That's going to make a real difference against the ongoing Russian aggression on the battlefield," he said.

Zelensky thanked Washington for the aid, which he said was "crucial" — but stressed it was "important to get it as quickly as possible".

"We need a noticeable acceleration of supplies. Now too much time passes between the announcement of packages and the actual appearance of weapons on the frontline," he said in an evening address.

Zelensky said air defence was the "biggest problem" for Ukraine and requested two Patriot batteries for the Kharkiv region, where Russian forces have been advancing and pounding villages along the border since Friday.

Blinken was on his fourth visit to Kyiv since Russia invaded Ukraine in February 2022.

After meeting Zelensky, he met Ukrainian Foreign Minister Dmytro Kuleba in Veterano, a pizzeria set up by a military veteran in the city centre.

Russia's surprise ground offensive in the Kharkiv region has forced thousands to evacuate and pushed Kyiv to mobilise troop reinforcements.

Ukraine said several civilians have been killed by Russian fire in the region, including yesterday two aged 80 and 83.

The governor of the Kharkiv region said 15 people were wounded by Russian strikes in the border territory's largest city, also called Kharkiv.

One civilian, a 47-year-old man, was also reported killed in the city of Nikopol in southern Ukraine.

In a call to Zelensky, French President Emmanuel Macron condemned the "intensification of Russian strikes" and the Kharkiv offensive.

Russia's defence ministry, meanwhile, said its forces had captured another village in the Kharkiv region.

"Units of the North group of troops liberated the village of Bugruvatka in the Kharkiv region and advanced deep into the enemy defence," the ministry said in a statement.