This is reported by The Telegraph with reference to the three-part documentary "Putin against the West".

According to Johnson, he had a very long and "most extraordinary" telephone conversation with Vladimir Putin.

In his speech, the ex-prime minister of Great Britain noted that the outbreak of hostilities in Ukraine would be a “complete disaster”, as it would lead to anti-Russian sanctions. 

“The Ukrainian side will be able to count on the support of Britain,” Johnson added.

Earlier, Boris Johnson called for Ukraine to join NATO.

He also called the Normandy format for a settlement in Ukraine "diplomatic imitation."