Ukrainian President Volodymyr Zelensky has said his chief of staff, Andriy Yermak, has resigned following an anti-corruption raid on his home.

Yermak, a towering figure with enormous political influence, has been Zelensky's closest adviser throughout Russia's full-scale war, but has come under increasing pressure over an escalating scandal - even though he is not accused of any wrongdoing.

Zelensky had recently appointed him to head crucial negotiations, with US President Donald Trump leading a new drive to end the Russia-Ukraine war.

In a stark address to the nation outside his presidential office, Zelensky called for unity, warning: "We risk losing everything: ourselves, Ukraine, our future."

The corruption scandal has rocked Ukraine for weeks, weakening Zelensky's own position and jeopardising the country's negotiating position with the US at a delicate time.

Ukraine, backed by its European allies, has sought to change the terms of a US-led draft peace plan originally seen as heavily slanted towards Russia.

Early on Friday Ukraine's two anti-corruption agencies raided Yermak's apartment in Kyiv's government quarters and the chief of staff said on social media that "from my side there is full co-operation".

"I'm grateful to Andriy that Ukraine's position on the negotiating track was always presented as required: it was always a patriotic position," Ukraine's president said during his video address in Kyiv.

Zelensky said he would start consultations on Saturday on who would replace Yermak as his top adviser: "When all the attention is focused on diplomacy and the defence in a war, inner strength is required."

"Russia wants Ukraine to make mistakes – there won't be any mistakes from our side. Our work continues, our fight continues. We have no right... to retreat, to quarrel [among ourselves]."

Yermak's departure from Ukraine's leading circle will come as a major blow for Zelensky, with US Army Secretary Dan Driscoll due to arrive in Kyiv by the end of this week as part of Trump's draft peace plan.

US officials are heading to Moscow next week and Russia's Vladimir Putin said on Friday he backed a Hungarian offer to host a Trump-Putin summit in Budapest.

Putin has continued to promote Russia's maximalist demands to bring an end to the war. He claimed on Thursday that Russian forces had the initiative on the battlefield and the fighting would only end when Ukrainian troops withdrew from the entire eastern Donbas region, including several strategically important cities under Ukrainian control.

"If they don't withdraw, we'll achieve this by force of arms," Putin he said.

Hours before the raid on his flat, Yermak continued to explain his government's position as it comes under US pressure to make territorial concessions to Russia, which launched a full-scale invasion of Ukraine in February 2022.

"As long as Zelensky is president, no-one should count on us giving up territory. He will not sign away territory," Yermak told The Atlantic website.

Yermak, 54, admitted during his interview he was under "enormous" pressure to stand down, adding "the case is fairly loud, and there needs to be an objective and independent investigation without political influence".

Investigators have linked several high-profile figures to an alleged $100m (£75m) embezzlement scandal in the energy sector.

Ukraine's anti-corruption bureau Nabu and specialised anti-corruption prosecutor's office (Sap) said they had uncovered an extensive scheme to take kickbacks and influence state-owned companies including state nuclear energy firm Enerhoatom.

Russian officials involved in Trump's draft peace plan have talked up the corruption claims, which have alarmed European Union allies. Ukraine is a candidate to join the EU and a report earlier this month highlighted doubts over "commitment to its anti-corruption agenda".

Earlier this year Zelensky sought to curb the powers of the two anti-corruption agencies, but he was forced to backtrack almost immediately after widespread protests and objections from Kyiv's Western allies.

Zelensky has already fired two ministers and several suspects have been detained in the burgeoning corruption scandal that has outraged public opinion because of allegations that money was diverted from key infrastructure projects vital for safeguarding Ukrainian power supplies.

As winter starts in Ukraine, Russian attacks have already badly damaged its energy infrastructure and Ukrainians across the country have had to cope with only a few hours of electricity a day.

One of the president's former business associates, Timur Mindich, has left the country in the wake of the corruption allegations.

Mindich was co-owner of the TV studio Kvartal 95 where Zelensky's acting career took off before he was elected president.

In recent weeks Andriy Yermak's popularity has nose-dived and MPs from all parties, including his own, have been calling for his sacking, initially for what they saw as his inflated power for an unelected official, but more recently, the burgeoning corruption scandal.

Recent polling suggested 70% of the public wanted him to resign.

Zelensky and his now-former chief of staff became friends about 14 years ago, while the future president was a senior media executive and Yermak worked for him as a lawyer. Yermak was made chief of staff a year after Zelensky was elected president in 2019.

On the first night of Russia's invasion, they appeared together with colleagues delivering a defiant video message outside the presidential office on Kyiv's Bankova Street, vowing to stay and fight.

"We are all here," Zelensky told Ukrainians. "Our soldiers are here, the citizens are here and we are all here. We are defending our independence, and that's how it will continue."