London, SAEDNEWS: Liz Truss told the Sunday Telegraph that Moscow would also have to commit to "no further aggression" or face the prospect of them being reimposed.
The West had to remain "tough to get peace", she said.
The UK, US, and EU have so far imposed sanctions on over 1,000 Russian individuals and businesses.
This week saw Moscow announce it would be refocusing its military operations in Ukraine to the country's east.
The move was interpreted by many as a sign that the Kremlin was looking to scale back an invasion that has so far made significantly less progress than was widely expected.
Ms Truss said that a negotiations unit had been set up to assist Ukraine once the Russians were "serious" about negotiations, but added: "I don't believe they are serious at present."
"That's why... we need to double down on sanctions," she said.
The foreign secretary has previously said she believes the peace talks are a "smokescreen" designed to distract from Russia's actions and allow its armed forces time to regroup (Source: BBC).
Russia: Biden’s son secretly funded bioweapons labs in Ukraine
