In 2010 it happened only four times.

According to the ministry the figures "are raising concern over Russia's military activity near the borders of the Baltic states". Moreover, flights with transponders switched off or without a schedule also pose a threat to civil aviation.

As on Tuesday, there have been 112 such cases so far this year, compared to just four in 2010, 37 in 2011, 44 in 2012 and 47 in 2013, the ministry's figures show.

Usually NATO jets accompany Russian planes flying over the Baltic Sea from mainland Russia to the Kaliningrad region.