A Russian border guard official and his wife are in critical condition with severe burns at separate hospitals here, after being attacked with a firebomb in their home on Sakhalin, the hospitals said Wednesday.

Vitalii Gamov and his wife, Larissa Gamova, were severely burned when someone threw a firebomb into their home in Yuzhno-Sakhalinsk early Tuesday. They were flown to Hokkaido on a plane chartered by Russia and arrived a little after midnight.

Gamov was in charge of patrols against poachers in the sea near the Russian-held islands claimed by Japan off Hokkaido. Sakhalin police were investigating the attack as attempted murder.

According to Sapporo Medical University Hospital, where the husband was taken, and Sapporo City General Hospital, where the wife is being treated, both sustained burns over 90 percent of their bodies, making it difficult to perform skin grafts.

The hospitals said they have put the two in intensive care units to manage their respiration and blood pressure, but it will be difficult for them to recover from the shock.

Yasufumi Asai, chief of the emergency ICU at Sapporo Medical University Hospital, said Gamov had remained conscious up to the point where they inserted a tube into his throat, and had told hospital staff that he wanted ice.