Smugglers who use the Narva River to cross into Estonia may move underwater as technological advances make it more difficult to avoid detection, the Police and Border Guard Board (PPA) has said.
The river, which divides Estonia and Russia, is already patrolled by both sides and is well guarded. Technological solutions - which are not discussed publically - are also used, ETV's current affairs show "Aktuaalne kaamera" (AK) reported on Monday evening
Border guards are not concerned about migrants crossing the river although in summer some people do try to swim across. But the fight against smugglers is a bigger challenge.
"Everything seems to be visible on the water, but at the same time, we don't know what's going on under the water," the PPA's Raivo Metsma, head of the Narva cordon, told AK.
"Those with experience can swim themselves, if there is scuba equipment, then you can swim from one place to another and no one may see anything happening on the water."
Metsa said the guards work with the local community so they can alert the PPA if anything is spotted. Increasingly modern technology, such as drones, is being used.
Currently, six boats patrol the Narva border section - two from Estonia and four from Russia. They often meet on the river and greet each other politely.
Editor: Helen Wright