The capital Kyiv remains under Ukrainian control as does Kharkiv in the east despite heavy Russian bombardment. Russian forces have seized Kherson in the south and have encircled urban centres in the region.

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

- The east

Kharkiv remains in Ukrainian hands despite intense bombardments, according to Western sources.

Russian forces are also pressing an offensive through the Russian-backed separatist Donetsk and Lugansk regions although how far they have penetrated remains unclear.

- Kyiv and the north

Kyiv remains under Ukrainian control, despite heavy bombardments, although Western observers have pointed to a major Russian column of hundreds of vehicle outside the city stationed around the Hostomel airfield.

There has been heavy fighting in the vicinity of Hostomel but the column has made little progress in recent days.

Regional authorities said 47 people were killed in a Russian air strike in the northern city of Chernigiv.

Zhytomyr west of Kyiv has also come under heavy fire.

- The south

Ukraine this week acknowledged that Russia had taken control of the southern city of Kherson, the first urban centre that Moscow has captured.

A major fight is ongoing for the city of Mariupol, still under Ukrainian control, while Mykolayiv just west of Kherson is surrounded.

In Zaporizhzhia, Europe's largest atomic power plant was attacked and seized by invading Russian forces in a move that sparked international outrage.

Odessa remains in Ukrainian control and for now spared of fighting although there are fears of a possible amphibious assault on the city with Russian warships lurking off the Black Sea coast.

- The west

The west of Ukrainian remains largely spared from the fighting. The main western city of Lviv has become a hub for foreign diplomatic missions, journalists and Ukrainians seeking safety or seeking to leave the country.

- Casualties

Russia said Wednesday that 498 Russian troops had been killed in Ukraine, its first announced death toll.

Ukraine and Western sources claim that the real toll is far higher. Ukraine says over 9,000 Russian soldiers have been killed.

The UN said Wednesday that it had recorded nearly 230 civilian deaths in Ukraine, including 15 children, warning that the true toll was likely far higher.

- Refugees

Over 1.2 million refugees have fled Ukraine in the week since Russia's invasion, around half of them into Poland, according to the UN refugee agency.