Moscow: Russian intelligence on Wednesday warned of an increased risk of Taliban or Islamic State fighters invading Central Asia.
FSB director Alexander Bortnikov said in comments carried by Russian news agencies that a concentration of Taliban fighters, some of whom had pledged allegiance to the Islamic State group, at Afghanistan's northern border make the risk of invasion tangible.
Afghanistan shares a porous border with the former Soviet republics of Turkmenistan, Uzbekistan and Tajikistan that has been a source of drugs coming into Russia and is a longstanding worry of Moscow's.
Russian President Vladimir Putin earlier this month called the situation in Afghanistan "close to critical" and urged other ex-Soviet nations to be prepared to act together to repel a possible attack.
In Moscow, meanwhile, a district court on Wednesday arrested a 19-year-old university student who was detained in June in Turkey as she was reportedly trying to cross the border into Syria.
Russian media reported at the time that Varvara Karaulova, a student at prestigious Moscow State University, went missing a few weeks before she was detained in a Turkish border town.
The reports said Karaulova, who had adopted Islam, aimed to go to Syria and join the Islamic State group.
Russian television said Karaulova, who has since changed her name to Alexandra Ivanova, will stay behind bars until the end of December on suspicion of conspiracy to acts of terrorism.
Russian investigators suspect she was aiming to recruit Russian volunteers to go to Syria.