"Data from the onboard GPS system and air force radars, as well as the Pacific Fleet, indicated the FSB An-72 plane tracking a Japanese boat poaching in the Sea of Japan did not violate Japan's border," an official of the FSB's coast guard department of the Far East island of Sakhalin was quoted by the Interfax news agency as saying.

    "Our plane came no closer than three kilometers from the border," the official said.

    The plane took off after an unidentified poachers' boat defied warnings from a coastguard cutter chasing it and headed toward Japanese territorial waters, the official said.

    The Japanese Defense Agency said on Wednesday a plane of Russia's coast guard service entered Japanese airspace without permission some 20 kilometers northeast of the Rebun island in the Sea of Japan.

    Japan scrambled six fighter aircraft from Hokkaido and sent radio warnings to the Russian plane, the agency said.

    Japan has protested the alleged Russian intrusion and demanded explanations from Moscow. Enditem