Black market tickets for flights from Moscow to Belgrade have soared to nearly €9,000, Serbia's president has claimed.
Aleksandar Vučić was speaking after Russia's call-up of reservists to fight in Ukraine sparked a rush on airline websites.
Flights with Air Serbia -- from Russia to Belgrade -- were sold out for this month and selling for €1,600 for travel in October on Thursday, up from about €850 mid-day Wednesday.
But Vučić claimed they were being resold for several times that figure.
"Today, Moscow-Belgrade flight ticket jumped to almost €9,000 on the black market because of the mobilisation and many other reasons," Vučić told the country's news agency Tanjug.
Searches in Russia for the terms "tickets" and "aeroplane" more than doubled from 08:00 CEST on Wednesday -- and immediately after Putin's announcement -- compared with the start of the week, according to the Google Trends statistical tool, which tracks how often a word was typed on Google in a certain location.
The request "to leave Russia" was carried out 100 times more in the morning than in normal times.
Tickets for direct flights to destinations closest to Russia -- Armenia, Georgia, Azerbaijan and Kazakhstan -- sold out on Wednesday, according to the Aviasales.ru site, very popular in Russia for buying tickets.
Meanwhile, flights from Russia to Istanbul -- which since the onset of Western sanctions have been one of the main routes out of the country -- with Turkish Airlines are sold out until next Tuesday.
Domestic flights to cities close to the country's borders exploded. Tickets from Moscow to Vladikavkaz -- near the border with Georgia -- have been costing €750, against around €70 normally.
At the same time, lines of cars were reported to be headed from Moscow to St Petersburg and further on to the Finnish border.
But Euronews has debunked online claims that queues at the Russia-Finland were stretched back 35 kilometres.
Nevertheless, traffic arriving at Finland's eastern border with Russia "intensified" overnight on Wednesday, the Finnish Border Guard said early on Thursday, while adding that the situation was under control.
Finnish border guard's head of international affairs, Matti Pitkaniitty, said 4,824 Russians arrived in Finland via the eastern border on Wednesday, up from the 3,133 a week earlier but still lower than last weekend.
Finland is closely monitoring the situation in neighbouring Russia following Putin's military mobilisation order, Finland's defence minister Antti Kaikkonen said on Wednesday.
Border crossings with Georgia and Mongolia have also seen an uptick in incoming traffic overnight, according to local media outlets.