Prime Minister David Cameron on Thursday warned that Britain would be left defenceless against the "highly unpredictable and aggressive" North Korean regime if it wound down its Trident nuclear deterrent programme.

Writing in the Daily Telegraph newspaper, Cameron said the recent actions of North Korea coupled with concerns over Iran's nuclear programme meant it would be "foolish" to scrap the fleet of nuclear missile submarines.

"We need our nuclear deterrent as much today as we did when a previous British government embarked on it over six decades ago... The Soviet Union no longer exists. But the nuclear threat has not gone away," he wrote.

"The highly unpredictable and aggressive regime in North Korea recently conducted its third nuclear test and could already have enough fissile material to produce more than a dozen nuclear weapons.

"Does anyone seriously argue that it would be wise for Britain, faced with this evolving threat today, to surrender our deterrent?"

Tensions have been rising on the Korean peninsula, with Pyongyang saying on Thursday that it had approved plans for nuclear strikes on US targets.

Cameron's Conservative Party is at odds with its junior coalition partners, the Liberal Democrats, over the Trident programme.

The Lib Dems want Britain to consider a cheaper alternative to the Conservatives' 20 billion pounds $30 billion, 23.5 billion euro) plan to replace the Trident submarines, which will approach the end of their working lives from the 2020s.

Cameron is committed to maintaining the submarine-based system, which Britain has had since the 1960s.