WARSAW, Sept 8 (Reuters) - The EU is preparing for an influx of Afghans seeking asylum, whether or not people flee en masse from the new Taliban government, the chief of the EU border agency said, noting that millions are already displaced in neighbouring countries. In an interview, Fabrice Leggeri, director-general of border agency Frontex, told Reuters the body was preparing for a possible surge, both through traditional routes such as from Turkey to Greece, and new routes such as via Belarus, which Brussels accuses of sending illegal migrants across the frontier. Frontex is "monitoring what"s going on" inside Afghanistan itself, but also keeping an eye on Afghan communities in neighbouring states, he said, listing Iran, Pakistan, Turkey, Tajikistan, Uzbekistan and Turkmenistan. "Our expectation is that depending on what"s going on in Afghanistan of course people in need of international protection might try to flee from Afghanistan. But what will very likely happen first is that the Afghan communities living abroad might try to move to the European Union." The EU has sought to reform its migration system after a crisis in 2015-2016, when more than a million people arrived, most crossing the Balkans on foot to reach northern Europe. The EU is now better at returning migrants who do not have a valid asylum claim to their country of origin, Leggeri said. As long as it is unsafe to send Afghans home, migrants from other countries may be tempted to pose as Afghans to gain entry. Leggeri said border guards were better now than six years ago at determining where people are from. "Now you cannot return Afghan people to Afghanistan. Of course we cannot. But we can return people who pretend they are Afghani people and they are not," he said. Experts now posted to the EU"s external borders can assess the nationality of a person by listening for dialects and ways of speaking, he said. Afghan migration could become entangled in Europe"s dispute with Belarus, which the EU accuses of flying in migrants from the Middle East to send them illegally across the border, causing a 1,500% spike in irregular arrivals into Lithuania. Minsk denies fostering illegal migration but says Europe must lift sanctions if it wants it to stop. "What happened with Belarus clearly opened the eyes of everybody," Leggeri said. "The way of pushing in migrants deliberately...Criminal networks want to make money but state organizations, they want to deal with geopolitics and this is another story." "It depends on geopolitical factors whether, lets say, the crisis in Afghanistan from a migration perspective might be linked to the crisis we have in Belarus."