The heartbroken family of a North submariner killed in an explosion beneath the polar ice cap spoke last night of their devastation.

Anthony Huntrod had only been aboard HMS Tireless for about three weeks when an emergency oxygen cylinder blew up as he was right next to it.

The 20-year-old, from Sunderland, was killed alongside 32-year-old colleague Paul McCann from Halesowen in the West Midlands. A third man also suffered serious injuries.

A rescue operation was immediately launched over the Arctic, involving a Hercules aircraft and helicopter support, and crew members from the nearby USS Alexandria boarded the nuclear submarine to help in the aftermath.

Both subs were dispatched to the area at the beginning of March to test the extreme conditions and carry out environmental studies as part of the joint exercise `Icex'.

A statement released by Anthony's family last night painted a picture of a young man who lived for his job.

It said: "Anthony was our son. We will miss him. He will be greatly missed by us for the rest of our lives.

"He was over the moon when he joined the Navy two years ago. He greatly loved the Navy and the job that he did."

Shortly after signing up, Anthony joined the crew of HMS Tireless where he qualified as a submariner, gaining the prestigious `Dolphins' badge after intensive training.

The Ministry of Defence paid testament to his positive approach, determination and huge heart which earned him the admiration and trust of the ship's company.

Colleagues said he had "infectious enthusiasm" and was a personable and respected young man who was eager to advance through the ranks. The operator maintenance weapons submariner recently joined the sub's combat computer section.

His commanding officer, Commander Iain Breckenridge, said: "I consider myself fortunate and privileged to have worked with such a committed, capable and effervescent young man and it was rare that I talked to him without both of us breaking into beaming smiles.

"Anthony stood at the cusp of a successful career. His loss has been profoundly felt by all on board but our thoughts are very much with his family and friends, to whom every man onboard HMS Tireless passes his deepest sympathy."

The MoD said yesterday that it is still not known why the 2ft x 3ft cylinder, one of two `last resort' emergency oxygen supplies to the vessel, that was fitted in 2001 and was bolted to the floor, exploded on Wednesday, but the Royal Navy is now thought to have temporarily banned the use of similar devices in the fleet.

A spokesman said: "It is still too early to say why this incident occurred but an investigation is taking place. However, I can say that damage to the vessel was minimal and it was nowhere near the nuclear core or any of the weapons systems."

House of Commons leader Jack Straw offered his condolences on behalf of MPs to the relatives of the two submariners.

"We send our sympathy to the families and the colleagues of those two sailors who were killed," he said.

Mr Straw, who was speaking in the Commons, added: "Those of us who have been on board submarines know just what a potentially dangerous environment it is and the safety record of the Royal Navy overall is second to none."

The third crewman involved in the incident, who is not being named, is still in an Alaskan hospital with injuries that are said to be not life-threatening.

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Tireless has troubled record

Hms Tireless, based at Devonport Dockyard in Plymouth, is a troubled vessel that has sparked major environmental and safety concerns in the past. In service for 22 years - but not regarded as an elderly submarine - it has been involved in at least two potentially serious incidents in the last few years.

In May 2000, a leak was discovered in its coolant system close to the nuclear reactor and it was forced to limp into Gibraltar for repairs.

Environmentalists were outraged as what turned out to be Tireless's year-long visit began, raising serious fears about nuclear contamination, and political relations between the UK and Spain became strained. Faults, discovered while it was in dock, led to a dozen other subs being taken out of service for major safety checks.

Then in 2003, while on patrol in the Arctic, it was involved in a collision with what was thought to have been an iceberg, where it suffered damage to its ballast tanks.