Latvia’s border guards have accused the authorities in neighbouring Belarus of being partly responsible for the construction of migrant tunnels beneath the fence on the border.

“It is simply impossible to build such a tunnel without the Belarusian border guards being aware of it,” Guntis Pujats, head of the agency, told Latvian radio on Thursday.

He was referring to a secret passage discovered last week beneath the now heavily secured EU external border between Belarus and Latvia.

Pujats said the entrance on the Belarusian side was situated 10 metres from the frontier and was concealed by trees and bushes. The tunnel itself was 80 centimetres high and wide, and at least 30 metres long.

A total of 28 cubic metres of earth had been excavated for its construction. In addition, solid support structures had been erected and a plywood covering fitted.

“The construction work was quite extensive. So the relevant authorities were undoubtedly aware of it,” he said.

He suspected that the excavation work on the tunnel was being monitored from the Belarusian side and halted as soon as a Latvian border patrol approached.

Latvia – like Lithuania and Poland – has repeatedly accused the authoritarian government in Belarus of systematically smuggling migrants from crisis-hit regions to the EU’s external border.

The governments of the three countries responded by stepping up border security and erecting a border fence, which migrants have so far mainly attempted to breech using homemade ladders or metal cutters.

Recently, however, border guards have been discovering an increasing number of underground smuggling routes.

Pujats said twelve tunnels have been discovered in Lithuania and two in Latvia so far.