Sweden says it has scrambled fighter jets to intercept two Russian military planes flying near the country's airspace over the Baltic Sea.

Military spokesman Jesper Tengroth says the Russian planes approached across international airspace near the southern Swedish island of Oland on Thursday morning. He did not specify the type of aircraft but local daily Dagens Nyheter said they were Tupolev TU-22M bombers.

Sweden's Supreme Commander Sverker Goranson told Swedish broadcaster Sveriges Radio that it was a "clear indication" of increased Russian military activity in the region and "an obvious signal to the outside world."

The incident comes a day before the Arctic Challenge 2015 military air exercises begin in the region, with some 100 fighter jets from U.S. and NATO joining Finnish and Swedish aircraft.