The Ministry of Defence was reported to be stepping up efforts to secure a share of the Government's aid budget as Whitehall wrangling continued ahead of the spending review.
According to the Guardian, the MoD has suggested the Department for International Development should pay for flights on military aircraft, some navy patrols and body armour.
The newspaper reported there was even a plan to ask DfID to contribute to the cost of the Royal Navy's new aircraft carriers on the grounds they could take part in peacekeeping operations or disaster relief effort, but that suggestion was later dropped.
A MoD spokesman said: "Improving stability and security in fragile and conflict-affected states is vital to our national security - that's why we're working with DfID to look at how best we can use our resources overseas ahead of a discussion at the National Security Council before the summer."
Emma Seery, Oxfam's head of development and finance, told the Guardian: "The UK made an historic commitment and it must stick to it and not look for loopholes in the rules. That would be unacceptable. It would not be acceptable for a single penny of the aid budget, which is supposed to be helping the world's poor, to be diverted to the military budget."
The overseas aid budget is protected from cuts and is regarded enviously by ministries which will be expected to make further savings when George Osborne announces spending plans for 2015/16 on June 26.
In February David Cameron indicated that he was ready to consider using money from the aid budget to fund military operations to stabilise war-torn states in the developing world.
He said: "DfID and the Foreign Office and the Defence Ministry work increasingly closely together. If you are asking me can they work even more closely together, can we make sure that the funds we have at our disposal are used to provide basic levels of stability and security in deeply broken and fragile states, then I think we should."
Any cut in the DfID budget could threaten to breach Cameron's pledge to meet the United Nations target of spending 0.7% of national income on overseas aid and would be met with dismay from charities and non-governmental organisations.
On Monday, the South African government criticised the UK's decision to stop direct aid in 2015, and concentrate on trade relations. The country said it had not been properly consulted over the move and it would have "far-reaching implications".
International Development Secretary Justine Greening made the announcement at a conference of African ministers and business leaders in London on Tuesday.
Deputy Prime Minister Nick Clegg acknowledged there had been "argy bargy" over the latest squeeze on budgets but he insisted that the Government was right to protect health, schools and international aid from cuts.
Clegg said the departmental spending round currently being thrashed out would not be as "gory" as the last settlement but refused to say how badly non-protected departments will be hit.
Liberal Democrat Business Secretary Vince Cable and Conservative Cabinet Ministers, including Defence Secretary Philip Hammond, have lobbied for ring-fences to be lifted in an effort to limit the impact of cuts on their own departments.
Clegg told BBC Radio 4's World At One: "If you are Vince Cable and you are in a department which doesn't have that ring-fence, you know... Philip Hammond and others have made it quite clear directly and indirectly that they are marshalling their arguments about why their department needs to be shielded from savings.
"It's the nature of this Whitehall argy bargy that you get at this stage. Having said that, I fundamentally - I don't think Vince was saying this - but I am absolutely convinced that, at a difficult time like this, protecting our NHS spending, protecting spending on schools and honouring our international obligations to developing countries around the world, was a big decision, was a controversial decision but I think was the right one to take and the right one to stick to."