Capt. Igor Dygalo described the rescue effort as U.S. and British crews with robotic undersea vehicles raced to reach the site of the accident off the remote Kamchatka Peninsula in the Russian Far East.
Authorities could not say exactly how much air remained on the mini-sub, which was some 625 feet below the surface, but an admiral said Saturday the supply should last until the end of the rescue.
Dygalo said two ships had worked a cable beneath the sub entangled in an underwater antenna assembly that is part of Russia's coastal monitoring system. Officials initially said fishing net ensnared the sub's propeller as it participated in military exercises Thursday.
Dygalo said rescuers hoped to raise the sub to a depth of at least 165 feet, which would allow divers to reach the 44-foot-long AS-28 and help the crew swim to the surface.
Rescuers made contact with the crew Saturday evening and said their condition was "satisfactory" despite temperatures of 41 to 45 degrees in their vessel, Russia's Pacific Fleet commander, Adm. Viktor Fyodorov, said.
It wasn't clear how contact was being made or why it was only intermittent.
"I assure you, work is continuing without interruption through night and day and will not stop until we actually lift our guys up to the surface," Fyodorov said in televised comments.
U.S. and British planes flew in unmanned submersibles, known as Super Scorpios, on Saturday. They were being taken by ship to the accident site and could be used to cut the sub loose from the entangling equipment if the Russian effort to lift the vessel failed. Russian news reports said the antenna array was held down by two concrete anchors weighing 60 tons.
The plea for international assistance underlined the deficiencies of Russia's once-mighty navy and strongly contrasted with the sinking of the nuclear submarine Kursk five years ago, when authorities held off asking for help until hope was nearly exhausted. All 118 crew died in that accident.
But even with Moscow's quick call for help, rescue workers were racing to free the men before their oxygen ran out.