Shafaq News/ British foreign minister Liz Truss said on Sunday there could be no talks with Russia over Ukraine while Moscow has troops in its neighbour.

Truss also said she had drawn up a "hit list" of Russian oligarchs and every few weeks the government would target their private jets, their properties and other possessions. The conflict could be protracted, she said.

Prime Minister Boris Johnson, under pressure over a series of parties at his Downing Street office and residence when Britain was under a strict COVID-19 lockdown, has wanted to take a lead in the West's response to the Ukraine crisis.

"Now if the Russians are serious about negotiations they need to remove their troops from Ukraine. They cannot negotiate with a gun to the head of the Ukrainians...So frankly, I don't trust these so-called efforts of negotiation," she told Sky News.

"I've compiled a hit list of oligarchs ... We are working through putting the cases together and every few weeks we will sanction new oligarchs. There will be a rolling programme of sanctions ...There will be nowhere to hide," she said.

But she said that sanctions would take time to degrade not only the Russian economy but also its "war machine".

"This could be a number of years, because what we do know is Russia have strong forces and we know that the Ukrainians are brave and they are determined to stand up for their sovereignty and territorial integrity."