Russian Air Force denied its military plane had intruded Japan's airspace, saying all the planes carried out tasks strictly in compliance with international regulations.

The Deputy Commander-in-Chief of Russian Air Force, Igor Sadofyev, said the flyby was part of a mission over neutral waters.

We have been carrying out the flights for several months and there were no complaints. Where these claims came from I don't know. I can only state that there were no violations of state border,

The Japanese Foreign Ministry said Saturday a Russian air force bomber briefly intruded into Japan's airspace in the morning and Japan had filed a strong protest over the intrusion.

A report said a Tupolev Tu-95 strategic bomber intruded Japan's airspace over the southern part of the Izu Island chain on Friday. The intrusion lasted about three minutes over areas near the uninhabited isle of Sofugan, about 650 km south of Tokyo.