LONDON — Britain's Royal Navy is to decommission its only helicopter assault carrier and hand the task over to one of the new aircraft carriers being built by BAE Systems.

Plans to scrap HMS Ocean in 2018 were part of the strategic defence and security review (SDSR) unveiled Nov 23. The decision to axe the Royal Navy's flagship only became known when it was briefly mentioned by defence minister Earl Howe in the House of Lords.

The ship, currently the largest in the Royal Navy, only completed a £65 million (US$97.8 million) refit last year.

The Royal Navy denied the warship was being axed earlier than planned.

"HMS Ocean will not decommission early and will continue in service as planned well into this Parliament. As part of the SDSR process, the decision was taken not to extend her and to decommission her in 2018, in line with her 20-year life span," the navy said in a statement.

The SDSR said that one of two 65,000-ton Queen Elizabeth-class carriers now being assembled at Rosyth in Scotland will be "enhanced" to support Royal Marine amphibious operations.

A Ministry of Defence spokesperson said HMS Prince of Wales, the second of the two carriers due for completion, would likely be earmarked for the addition of new systems to support amphibious operations.

The assault ships Bulwark or Albion, or HMS Queen Elizabeth, could help fill the gap until the Prince of Wales is ready early in the next decade.

Queen Elizabeth, the first of class, is scheduled to be commissioned in 2017 and start helicopter flight trials in the same year. Flight trials of the Lockheed Martin F-35B combat jets are set to get underway the following year.

Current plans do not envisage both carriers operating at the same time except in an emergency.