Russia denies claims military jet violated Estonia airspace

Russia has denied claims one of its jets violated Estonian airspace earlier this week.

It follows claims by Estonia that a Russian reconnaissance jet entered Estonian airspace without permission on October 21. 

"Russian Defense Ministry aircraft did not violate the airspace of the Republic of Estonia," a statement from Russia's Defense Ministry said.

According to the ministry, the reconnaissance plane was making a  training flight above the neutral Baltic Sea.

"The flight proceeded in strict accordance with international rules on the use of airspace," Russia's Defense Ministry added, according to the Interfax news agency. 

But Estonia's Air Operations Command Centre says the plane entered Estonian airspace for around a minute on Tuesday . It's transponder was turned off whilst it didn't make radio contact with the Estonian air traffic service.

In a response, Estonia's Foreign Ministry on Wednesday summoned Russian Ambassador to Estonia Yuri Merzlyakov for questioning.

Meanwhile, Baltic officials say they have noted a rise in the number of Russian warships and planes flying close to their borders amid the crisis in the Ukraine.

Swedish officials say they have credible reports of 'foreign underwater activity' in its waters last week. A search operation is on for what may be a Russian submarine after several 'credible' sightings. 

Speaking in Riga earlier this eek, Sweden's Prime Minister Stefan Lofven declined to speculate on the search.

"It's worrying, but we don't know what it is," the Prime Minister said.