A Russian drone has hit a train near the Ukraine-Poland border shortly after former UK Prime Minister Boris Johnson and top European security officials had passed through.

No casualties were reported after the strike at Yahodyn, which hit the train's engine.All the passengers had been evacuated, Ukrainian authorities said.

Johnson and other European national security advisers, including the UK's Jonathan Powell, had passed along the same line on a different train on their way back from a conference in Kyiv.

Russia said it had struck "railway infrastructure" in western Ukraine, but Ukraine's state railway company Ukrzaliznytsia said that "quite possibly, the target of this drone could have been the diplomatic train".

Former CIA chief David Petraeus, who had been on board another train at Yahodyn station at the time of the strike, said the incident was "terrifying".

In an interview with the New York Times, Petraeus said: "This is the act of a truly barbaric leader trying to terrorize Ukrainian civilians."

In a statement, Ukrzaliznytsia said the diplomatic train "had left the station earlier than expected because of the timetable change... due to constant threats of Russian strikes".

It also said an evacuation order for passengers on the hit train had been given "just 15 minutes" before the strike by a Russian jet-propelled drone.

Both Ukrainian and Polish authorities said the Russian drone had struck 2km (1.2 miles) from the Polish border.

Former Swedish Prime Minister Carl Bildt, who had also attended the conference in Kyiv, told the BBC passengers on board his train had been told to prepare for evacuation before subsequently being allowed to continue their journey.

"On the train I was on we received order to prepare evacuation after it had stopped. But after a number of minutes we were informed that it was clear and we could proceed," he said.

That train then safely arrived at Poland's border station in Dorohusk.

Some reports have suggested Bildt was on the same train as Johnson, but the former UK prime minister has not confirmed any details.

Johnson wrote on X: "I don't know what warped logic drove Putin to blow up a stationary Ukrainian locomotive on the Polish border this morning.

He said this was "the kind of random and senseless attack Ukrainians are enduring every day - even on civilian railways" and urged Kyiv's allies to urgently provide Ukrainians "the air defences they need".

Ukraine has made repeated pleas to its allies - particularly the US - to provide more interceptors to defend against daily Russian attacks that increasingly use fast-moving ballistic missiles and jet-propelled drones.

Ukrainian Foreign Minister Andrii Sybiha said the "barbaric strikes" at the Ukraine-Poland border in Yahodyn amounted to "[Russian President Vladimir] Putin's terror 'knocking' directly on the doors of the EU and Nato" and renewed calls for more sanctions on Moscow.

"Putin needs to understand that his barbarism will be met with decisive action that increases the cost of war for him to an unacceptable level. This is the only way to stop him," he said.

In Poland, Prime Minister Donald Tusk held an emergency meeting to discuss the latest developments.

"The escalation of the actions from the Russian side is becoming a reality, and they are getting closer and closer to our border."

The EU's foreign policy chief Kaja Kallas has accused Russia of attempting to scare Western countries with the attack.

"I think we should act the opposite. We should show that we are there for Ukraine and we are not scared," she told reporters in Finland during a summit on Arctic strategy.

Johnson and other top European security advisers were on their way back from the Yalta European Strategy (YES) conference in Kyiv - an annual event that brings together leaders and experts from politics, business, security and mass media.

Russia appears to be escalating its war against Ukraine by targeting trains, railway depots, petrol stations and border crossings.

Earlier this week, two people were killed when Russian drones hit a border crossing between Ukraine and Moldova, Ukrainian President Volodymyr Zelensky said.

Also this week, a female conductor died in a Russian drone attack on a passenger train in southern Ukraine. Six Ukrzaliznytsia employees were killed after a depot was struck in Kyiv at the start of the month.

In January, Zelensky condemned as "terrorism" a Russian strike on a crowded passenger train in the north-eastern Kharkiv region that left five people dead.

The Russian attacks have significantly damaged Ukraine's vast train network - the main mode of transportation for millions of Ukrainians as all air travel has been suspended since the start of Russia's full-scale invasion in 2022.

European countries are also blaming Russia for suspicious incidents on their territory.

Last week, Germany said Russia was responsible for August's drone attack at Leipzig's airport - a claim denied by Moscow as "absurd".

There have also been a number of suspicious fires at defence facilities from Italy to Estonia, with some of the affected countries blaming Russia.

Russian authorities have also accused Ukraine of targeting trains and busses in recent months.

Last year, Ukraine's Security Service (SBU) said it targeted a railway bridge in Crimea following an operation lasting "several months".

The Crimea bridge - also known as Kerch Bridge - was built by Russia after it invaded and annexed the Crimean Peninsula in 2014. It was inaugurated by Russian President Vladimir Putin to great fanfare in 2018.