Gunfire has been heard near the government quarter of the Ukrainian capital, according to reports.

The Associated Press is reporting gunfire in Kyiv as Ukraine's presidential advisor said Russia is planning to capture the capital and kill the Ukrainian president, Volodymyr Zelenky.

A tweet from the Ukraine defence ministry suggests Russian forces have reached the city as citizens are urged to "make Molotov cocktails" to defend their city.

A translation of the tweet reads: "In Obolon, the enemy DRG. We ask citizens to inform about the movement of equipment! Make Molotov cocktails, neutralize the occupier! Peaceful residents - be careful! Do not leave the house!"

It comes the day after Boris Johnson said the UK will offer support for the Ukrainian government in exile as the Prime Minister warned Volodymyr Zelensky he may need a “safe space”.

Asked whether the UK would offer sanctuary Mr Johnson replied: “Of course we will give all support that we can – logistical or otherwise – as Britain always has done to governments in exile.”

Ukrainian President calls for tougher sanctions on Russia

Zelensky has demanded tougher sanctions and support fending off the Russian invasion as Kyiv was hit by air strikes.

Mr Zelensky also called for allies to provide “effective counteraction” against Moscow’s advances after holding talks with Boris Johnson on Friday morning.

Downing Street said the Prime Minister pledged further support “in the coming days” after the president updated him on the “terrible developments” in the Ukrainian capital.

York Press: A map showing the locations of known Russian military strikes inside Ukraine (AP)A map showing the locations of known Russian military strikes inside Ukraine (AP)

Defence Secretary Ben Wallace said more than 450 Russian troops had been killed, as a fierce resistance meant Moscow “failed” on the main objective on the first day of fighting.

Mr Johnson and Mr Zelensky spoke after Kyiv was hit by “horrific rocket strikes” and fighting reached the outskirts of the capital overnight.

After the call, the president said Ukraine “needs the support of partners more than ever”.

“We demand effective counteraction to the Russian Federation. Sanctions must be further strengthened,” Mr Zelensky added.