British MPs and peers from all parties have called on the government to back Ukraine’s demands for a “just peace” with diplomatic pressure and military aid, as President Volodymyr Zelenskyy said his country aimed to reach a negotiated end to the war next year.

Donald Trump’s election victory has accelerated preparations for talks between Ukraine and Russia after nearly three years of war. He has repeatedly said he could end the war “in a day”, without detailing how.

Zelenskyy endorsed a rapid push to broker a deal on Saturday. “From our side, we must do everything so that this war ends next year, ends through diplomatic means,” he told Ukrainian radio. On Friday, he played to Trump’s “deal maker” reputation, saying his election victory means the conflict will “end sooner”.

In a signal that Ukraine’s backers are preparing for talks, German chancellor Olaf Scholz spoke to Vladimir Putin on Friday, in the Russian president’s first call with a major western leader since late 2022. He urged Putin to withdraw his forces and come to the negotiating table.

Zelenskyy has assiduously courted Trump to push for a different vision, meeting him in New York in September. After Trump’s victory, the Ukrainian leader was quick to congratulate him, quoting with approval Trump’s own promise of “strength through peace”.

He has pitched to Trump his “victory plan”, which calls for better defence capabilities and a strategic non-nuclear deterrent, including an unconditional invitation to join Nato.

Keir Starmer’s government must back Ukraine strongly in the coming months, as both sides seek to shore up their position ahead of negotiations, the all-party parliamentary group on Ukraine said in a statement marking 1,000 days since Russia’s full-scale invasion. That grim anniversary falls on 19 November.

“International support is crucial for achieving a just peace,” the statement says. “The victory plan is aimed at ensuring that the war does not last indefinitely and that it ends on fair terms, with Ukraine’s sovereignty ensured and Putin’s plans failed.”

Trump’s vice-president, JD Vance, outlined during the campaign a plan that critics describe as tantamount to a Russian victory, with Moscow keeping de facto control over Ukrainian territory it occupies now and Ukraine left outside Nato.

Downing Street insists its support for Ukraine remains “iron clad” even as the recent appointment of Jonathan Powell as the government’s national security adviser suggested it is also preparing for attempts to negotiate an end to the war.

Powell, who served as Tony Blair’s chief of staff throughout his premiership, led successful negotiations for peace in Northern Ireland. In recent years he has been running his own charity Inter Mediate, which works to broker peace deals in many of the world’s conflict zones.

Last year Powell, said in Prospect magazine that world leaders should prepare for a negotiated settlement between Russia and Ukraine.

Ukraine’s government, which once insisted it would fight until all its territory had been liberated, now accepts the war is likely to end in talks and that any deal would mean the loss of some areas held by Russian forces, which currently occupy around 20% of the country.

Britain must back Kyiv’s position on possible concessions, rather than pushing Zelenskyy to agree to Russian demands, said the parliamentary group’s chair, Alex Sobel, a Labour MP. “No other country has the authority to negotiate away the territory of Ukraine,” Sobel told the Observer. “This statement demonstrates renewed support from parliamentarians in the UK given the evolving international situation.”

The Wall Street Journal claims one idea being considered in Trump circles is for an 800-mile demilitarised zone between the Russian and Ukrainian armies, with the current front line frozen. Ukrainian ambitions to join Nato would be shelved for at least two decades, but the US would provide weapons to deter future Russian aggression.

The nature of any security guarantee is key for Ukrainians, who fear Moscow would exploit a weak deal to prepare for another attack. In 2022, Putin declared that the Minsk Accords, negotiated after Russia seized Crimea and its proxies took parts of eastern Ukraine, “do not exist”, and launched an invasion.

The UK must offer Ukraine “steadfast and unwavering commitment” as it prepares for a difficult year, said Sarah Green, the Liberal Democrat MP for Chesham and Amersham, co-chair of the parliamentary group.