Japanese Prime Minister Fumio Kishida is en route to Ukraine for a surprise visit after pressure to travel there as this year's host of the Group of Seven summit.
National broadcaster NHK, along with outlets including the Kyodo news agency cited an unnamed government source as saying Kishida would arrive in Ukraine on Tuesday after talks in India.
NHK said its reporters in Poland had filmed a car carrying the Japanese premier in the town of Przemysel, from where foreign leaders have often taken the train into Ukraine.
"The convoy entered the Przemysl station and parked in front of the platform used by international trains heading towards Ukraine. Prime Minister Kishida disembarked from the first car of the convoy and boarded the last carriage of the train."
The broadcaster said the train had left at 1:30 am (0030 GMT).
There was no immediate confirmation from Japanese government officials.
Kishida became the only G7 leader not to have visited Kyiv after US President Joe Biden made a surprise stop to meet Ukrainian President Volodymyr Zelensky in February.
Kishida had repeatedly said the trip was "under consideration" with government sources telling local media that there were security concerns and logistical challenges.
{{/usCountry}}Kishida had repeatedly said the trip was "under consideration" with government sources telling local media that there were security concerns and logistical challenges.
{{/usCountry}}He is the first Japanese prime minister to visit an active warzone in the period since World War II.
His trip comes with Chinese President Xi Jinping visiting Moscow for talks with Russian leader Vladimir Putin, with the Ukraine conflict high on the agenda.
Japan has joined Western allies to sanction Russia over its invasion of Ukraine, and offered support to Kyiv.
In February, Tokyo announced it would offer Ukraine fresh financial aid worth $5.5 billion, having already provided the country with hundreds of billions of dollars of emergency humanitarian assistance and other support.
It has also taken the rare steps of sending defensive equipment and offering refuge to those fleeing the conflict.
It has not offered military support, however, because the nation's post-war constitution limits its military capacity to ostensibly defensive measures.
Kishida warned in a speech last year that "Ukraine today may be East Asia tomorrow", as concerns grow that China could invade democratic, self-ruled Taiwan.
And in December, as Japan overhauled its key defence policies, the government explicitly warned that China poses the "greatest strategic challenge ever" to its security.
In its largest defence shake-up in decades, Japan set a goal of doubling defence spending to the NATO standard of two percent of GDP by 2027.