The RAF needs 'more investment' if it is to continue running the range of operations ministers demand, the head of the air force warned today.

Tornados from Marham have played a key role over the last two weeks. Some aircraft have flown 3,000-mile sorties from Norfolk to Libya.

Others have been deployed to Gioia del Colle - a forward operating base in southern Italy.

Air Chief Marshal Sir Stephen Dalton, who is overseeing a huge overhaul in the service, said the RAF was now stretched to the limit.

He added senior officers were now planning to continue operations over Libya for at least six months, with aircraft needed for 'a number of months rather than a number of days or weeks'.

The warning came as key figures in Col Gaddafi's regime appeared to be seeking an end to the crisis. Sir Stephen told the Guardian: 'The key factor is that if we are to meet the requirements laid upon us, there is no question that more investment will be needed to achieve that.

'What I am seeking to do is maintain core competencies and bricks on which we can then build the future.'

Without 'genuine increases', the RAF would find it 'very difficult to maintain levels of capability,' he said.

As Tornado crews take part in operations in Libya, the future of their base remains in doubt. Ministers say a decision over whether the Norfolk station or RAF Lossiemouth will become the Tornado force's main base will not be announced until at least May and could come as late as July.

One squadron which has flown 3,000-mile sorties from Marham to Libya, XIII, is due to be disbanded in June.

But senior officers expect most of its air and ground staff will be transferred to other squadrons or elsewhere in the RAF.

Last autumn, the Government signalled its intention to shed 17,000 posts, some through 'natural wastage', from the armed forces in a bid to save nearly �5bn over four years.

The RAF last month spelled out its plans for 2,700 lay-offs following last year's strategic defence and security review.

Today the Army and Navy unveiled the process under which they will make 5,000 and 3,300 redundancies respectively.

The MoD said the UK was committed to the ISAF mission in Afghanistan and current operations in Libya, and the changes would have no impact on current operations.

'No-one who is preparing for combat operations, deployed on operations or on post-operational tour leave on the day redundancy notices are issued will be made redundant unless they have volunteered,' a statement on its website said.

Sir Stephen said the RAF could continue its work in Afghanistan, the Falklands and Libya 'on current planning', but added: 'That does bring you nearer the point that you have just about exhausted the bag.

'It's a heck of a lot to be doing at one time.'

The immediate priority was British efforts in Libya, he said, where planning was 'on the basis of at least six months'.

The Government has set a target of 2020 for revamping the Uk's defence strategy.

Sir Stephen said extra cash was needed from the next comprehensive spending review in 2014-15, but claimed Prime Minister David Cameron had acknowledged this requirement, the newspaper said.

The RAF chief accepted the need for reform, but added: 'What we are seeking to do is make sure that the adjustments are recoverable (and do) the least long-term damage.'

Sir Stephen said air power was 'essential' for nearly all types of operations and warfare, and dismissed suggestions the service was too expensive.

He also stressed there was 'no question' the country needed an independent RAF.