Russia’s foreign minister Sergei Lavrov was forced to cancel a planned trip to Serbia after three of its neighbours refused access to their airspace following the war in Ukraine.
Bulgaria, North Macedonia and Montenegro all refused to allow Mr Lavrov’s plane to use their airspace, according to Serbian media.
Mr Lavrov had been due to visit the Serbian capital, Belgrade, on June 6.
A Kremlin source confirmed the news to Russia’s Interfax news agency, adding: “Our diplomacy has yet to master teleportation”.
Mr Lavrov is among a string of Kremlin officials to be sanctioned by the west over the invasion of Ukraine. But Serbia, which has close cultural ties to Moscow, has refused to take sides during the conflict.
Last month, Serbian President Aleksandar Vucic agreed a deal with Mr Putin to allow Russian gas to continue to flow to Serbia as other European countries diversified their energy imports.
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Moscow has previously supported Belgrade at the UN security council, blocking Kosovo’s independence.
In other developments, Russia struck Kyiv with missiles for the first time in more than a month on Sunday as Mr Putin warned he would hit new targets in Ukraine if western nations continued to deliver weapons. Last week, the US said it would send new, advanced medium-range rocket systems to Ukraine.
Speaking to Russian state television, Mr Putin said the rockets Washington had promised so far were comparable to Soviet-era weapons Ukraine already had.
If Washington were to deliver longer-range rockets, “we will strike at those targets which we have not yet been hitting”, he said.
He dismissed the impact of Western drones, saying Russia had been “cracking them like nuts”.
Britain said it would supply Ukraine with multiple-launch rocket systems that can strike targets up to 80km away.
In a Twitter update, Britain’s Ministry of Defence said heavy fighting was ongoing in the besieged town of Severodonetsk and Russian forces were pushing towards Sloviansk.