On the 19th day of Russia's invasion of Ukraine Monday, Russian forces were encircling at least four major cities and sought to increase pressure on the capital Kyiv.

The capital remains under Ukrainian control but is increasingly at risk of being surrounded, with many observers believing Russia is still aiming to capture the city despite slow progress and intense resistance.

Here is a summary of the situation on the ground, based on statements from both sides, Western defence and intelligence sources and international organisations.

Kharkiv remains in Ukrainian hands despite increasingly intense Russian bombardment, according to Western sources, and the city is now surrounded.

Prosecutors there said two people were killed and another injured in a Monday bombardment of a residential street, calling it a possible war crime, while a 15-year-old boy was killed in shelling of a kindergarten 40 kilometres (25 miles) away.

Russian forces were also pressing an offensive through the separatist Donetsk and Lugansk regions that are backed by Russia and seeking to join up with Russian troops who entered from the north.

Russian-backed separatists said fragments from a shot-down Ukrainian missile ripped the centre of Donetsk, killing 23 people -- quickly dubbed a war crime by Moscow, although Ukraine denied firing a missile at the city.

The city of Sumy in northeast Ukraine is now encircled by Russian troops but thousands of civilians have been able to leave through a humanitarian corridor.

Kyiv remains under Ukrainian control despite heavy bombardments, but observers say Russian forces are still slowly advancing ever closer towards the capital.

AFP journalists reported that the Ukrainian army was still offering resistance to both the east and west of the city, while at least two people were confirmed killed in Russian air strikes.

The northwest suburbs, including Irpin and Bucha, have already endured days of heavy bombardment but Russian armoured vehicles are also advancing on the northeastern edge.

Ukrainian forces also retain control of the northern town of Chernigiv, which has seen heavy civilian casualties in recent days and appears to be encircled.

Meanwhile electricity was once again cut to the former nuclear power plant at Chernobyl, energy operator Ukrenergo said, leaving cooling systems for spent fuel again relying on back-up generators.

Kyiv remains under Ukrainian control but is at risk of being surrounded
Kyiv remains under Ukrainian control but is at risk of being surrounded AFP / Cléa PÉCULIER

Russia has besieged the strategic city of Mariupol, and attempts to evacuate an estimated 200,000 civilians from the city have struggled -- although more than 160 civilian cars were able to leave Monday via a humanitarian corridor.

Local officials said nearly 2,200 people have been killed in the fighting so far and 400,000 are without running water or heat.

The major port city of Odessa remains under Ukrainian control and has so far been spared fighting. But the US Department of Defense said Russian ground forces appeared primed to attack the city, possibly in coordination with an amphibious assault.

Russian forces earlier this month took the southern city of Kherson, just north of Crimea, and there is now heavy fighting for control of the city of Mykolaiv to the northwest.

Ukrainian nuclear energy authority Energoatom accused the Russian military of detonating ammunition near the Zaporizhzhia nuclear power station -- Europe's largest.

Nine people died and another nine suffered injuries on Monday when Russian forces hit a television tower outside the western Ukrainian city of Rivne, about 200 kilometres northeast of Lviv, local authorities said.

The main city of Lviv has become a hub for foreign diplomatic missions and journalists as well as Ukrainians seeking safety or wanting to leave the country.

Meanwhile a US defence official said that a Ukrainian military base a few miles from the Polish border that was bombed overnight was hit by a "couple dozen" cruise missiles launched from planes within Russian airspace.

Speaking on condition of anonymity, the official added that the Sunday strike, which killed at least 35 people and wounded 130 more, did not hinder the shipment of Western weaponry and munitions to Ukraine forces.

The United Nations said Thursday that it had recorded 636 civilian deaths in Ukraine, including 46 children, though the actual toll could be far higher.

Ukraine and Western sources claim that the Russian death toll is far higher than Moscow has so far admitted.

Ukraine says more than 12,000 Russian soldiers have been killed. President Volodymyr Zelensky said Saturday around 1,300 Ukrainian troops had been killed.

Over 2.8 million refugees have fled Ukraine since the invasion began, more than half going to Poland, according to the UN refugee agency.