The officials said negotiations with US President Donald Trump's envoys, Steve Witkoff and Jared Kushner, led to narrowing differences on security guarantees that Ukraine said must be provided, as well as Russia's contentious demand that Ukraine concede land in the eastern Donbas region.
Trump was expected to dial into a dinner on Monday evening with mediators and European leaders, and more talks are likely this weekend in Miami or elsewhere in the United States, according to the US officials who spoke on the condition of anonymity.
The US officials said the offer of security guarantees would not be on the table "forever".
They said Trump's administration plans to put forward the agreement on security guarantees for Senate approval, although they did not specify whether it would be ratified like a treaty, which needs the chamber's two-thirds approval.
The US officials also said they had reached agreement on 90 per cent of the issues involved.
One said long-standing territorial issues remain but that "we've got multiple different solutions to bridge the gap that we are suggesting to them".
Calling the issue of territorial concessions "painful," Zelenskiy confirmed to reporters that differences over the matter persisted.
"Frankly speaking, we still have different positions," he said, adding, however, that he believed US mediators would help find a compromise.
Ukrainian negotiators would continue consultations with US counterparts, he said, adding that Ukraine needed a clear understanding on security guarantees, including the monitoring of a ceasefire, before making any decisions to do with the war's front lines.
"I do not think that the (US) has demanded anything," Zelenskiy said.
"I see us as strategic partners, so I would say that we have heard about the issue of territories in relation to Russia's vision or Russia's demands from the (US). We see this as demands from the Russian Federation."
"Over the past two days, Ukrainian-US negotiations have been constructive and productive, with real progress achieved," Rustem Umerov, secretary of the National Security and Defence Council, wrote on X earlier on Monday.
"The American team led by Steve Witkoff and Jared Kushner are working extremely constructively to help Ukraine find a way to a peace agreement that lasts."
A US official told reporters later that, under the deal being discussed in Berlin, Ukraine would receive security guarantees similar to those provided in Article five of the NATO treaty, which requires the alliance to come to the defence of any member that comes under attack.
Those guarantees would not be on the table forever, however, US officials cautioned.
One said Trump wanted to prevent Russia from encroaching further westwards.
One official said security guarantees, including de-confliction and oversight of any deal, were the major focus of Monday's talks and that an Article 5-like guarantee was something Trump believed he could get Russia to accept.
Ukraine said on Sunday it was willing to drop its ambition to join the NATO military alliance in exchange for security guarantees from allies.
Russia claims to have annexed Ukraine's eastern Donbas region comprising Donetsk and Luhansk as well as three other regions including Crimea, something Ukraine and its allies say is unacceptable.
with AP
