The Kremlin has denied reports that claimed the US President-elect Donald Trump has spoken with Russian President Vladimir Putin where the American leader reportedly urged Putin to not escalate the war in Ukraine.

Casting the media reports as “pure fiction”, Kremlin spokesman Dmitry Peskov on Monday said Putin has no specific plans to speak to Trump at the present.

“This is completely untrue. This is pure fiction, it’s just false information. There was no conversation,” Peskov told reporters.

“This is the most obvious example of the quality of the information that is being published now, sometimes even in fairly reputable publications,” Peskov said.

Asked if Putin had plans for any contacts with Trump, Peskov said: “There are no concrete plans yet.”

The Washington Post first reported that Trump held the call from his Mar-a-Lago estate in Florida on Thursday, just days after his stunning election victory over Democratic rival Kamala Harris.

The Post, quoting several people familiar with the call who spoke on the basis of anonymity, reported that Trump reminded Putin of the US military’s sizeable presence in Europe. They said he also expressed an interest in further conversations to discuss “the resolution of Ukraine’s war soon”.

Reuters news agency also said the call took place, citing sources who were not authorised to reveal their identities to the media.

Steven Cheung, Trump’s communications director, did not confirm the exchange, telling the AFP news agency in a written statement that “we do not comment on private calls between President Trump and other world leaders.”

Meanwhile, authorities in Ukraine on Monday issued a countrywide alert and introduced preventative power blackouts across several cities over threats of a new large-scale Russian attack.

“Attention! Missile danger throughout Ukraine! MiG-31K takeoff,” Ukraine’s air force said in a post on Telegram. “The air alert is related to the launch of cruise missiles from Tu-95MS strategic bombers,” it added.

Capital Kyiv’s military administration ordered an emergency blackout for the city, saying the power outages were due to imminent missile attacks. Ukrainian media reported similar orders for Mykolaiv, Cherkasy, Sumy, Zhytomyr, Kirovohrad, and Kharkiv.

Social media footage showed large numbers of people gathering in the city’s metro stations, which have served as bomb shelters since the start of Russia’s war on Ukraine in February 2022.

However, by 06:30 GMT, the missiles had not arrived. According to some Ukrainian military bloggers, the Russian bombers performed flights imitating the launch of missiles.

Monday’s air alerts wailed after Russian air attacks killed at least six people in southern Ukraine, and a day after Moscow and Kyiv launched record overnight drone attacks on each other.

Five people were killed in the southern city of Mykolaiv, according to the regional governor. About 300km (186 miles) to the east in Zaporizhzhia, Ukraine’s state emergency services agency said Russia carried out three air attacks that killed another man, wounded more than a dozen people and damaged multiple buildings.

Trump’s election is set to have a major bearing on the almost three-year Ukraine conflict, as he insists on a quick end to the fighting and casts doubt on Washington’s multi-billion-dollar support for Kyiv.

Ukrainian President Volodymyr Zelensky spoke with Trump on Wednesday, with the Republican’s billionaire backer Elon Musk also notably joining them on the call.

The outgoing Democratic administration of President Joe Biden has confirmed that it will send as much aid as possible to Ukraine before Trump’s inauguration on January 20.

On Sunday, Biden’s National Security Advisor Jake Sullivan said the White House aims “to put Ukraine in the strongest possible position on the battlefield so that it is ultimately in the strongest possible position at the negotiating table”. This would include using the remaining available $6bn of funding for Ukraine, Sullivan said.

While Trump has not gone into detail on how he plans to end the conflict, his incoming Vice President JD Vance has offered a rough vision.

“What it probably looks like is the current line of demarcation between Russia and Ukraine, that becomes like a demilitarised zone,” Vance said on the Shawn Ryan Show podcast in September.