Vladimir Putin and RT editor-in-chief and moderator Margarita Simonyan (R) attend a session of the St. Petersburg International Economic Forum on Friday. Reuters

Addressing the St Petersburg International Economic Forum, a showcase event this year being held with almost no Western participation, he told Russia's political and economic elite:

"We are strong people and can cope with any challenge. Like our ancestors, we will solve any problem, the entire thousand-year history of our country speaks of this."

Putin drew applause from the hall when he reaffirmed his determination to continue the "special military operation" in Ukraine that has unleashed what he said was an "unprecedented" barrage of Western economic sanctions.

He said the main aim of the incursion was to defend "our" people in the largely Russian-speaking Donbas region of eastern Ukraine - a justification that Kyiv and the West dismiss as a baseless pretext for a war that has already led to the occupation of parts of southern Ukraine far beyond the Donbas.

Putin said the Russian soldiers in the Donbas were also fighting to defend Russia's own "rights to secure development".

"The West has fundamentally refused to fulfil its earlier obligations, it turned out to be simply impossible to reach any new agreements with it," Putin said.

"In the current situation, against a backdrop of increasing risks for us and threats, Russia's decision to conduct a special military operation was forced - difficult, of course, but forced and necessary."

Putin said the United States considered itself "God's emissary on Earth", and that Western sanctions were founded on a false premise that Russia had no economic sovereignty.

Washington and its allies were trying to "change the course of history", he said, to weaken a sovereign, independent Russia.

Shortly before Putin was due to begin speaking, the Kremlin announced that a "denial of service" cyber attack had disabled the accreditation and admission systems of the conference, forcing him to delay the scheduled start of his speech by an hour.

Reuters