The capability of Britain's armed forces would be put at risk if defence spending is cut again in the government's next spending review, Defence Secretary Philip Hammond said Saturday.

"There may be some modest reductions we can make through further efficiencies and we will look for those, but we won't be able to make significant further cuts without eroding military capability," he told BBC television.

"We're already extremely taut.

"We have some very challenging targets ahead of us to deliver the outcome of the last spending review and I'm clear that we won't be able to deliver big further savings."

As part of the 2010 Strategic Defence and Security Review, the Ministry of Defence (MoD) faced an eight-percent budget cut in real terms over four years, forcing a shrinking in the size of the military.

With talks about to begin on the next public spending round after the 2015 general election year, Hammond said it was time other departments felt the pinch to the same degree.

Last month, Downing Street announced that the MoD would not be saved from further budget cuts as Britain continues trying to rein in its overspending.

"I am not going into the spending review offering any further reductions in personnel," Hammond told The Daily Telegraph newspaper.

"I shall go into the spending review fighting the case for the defence budget on the basis that we have made very large cuts to defence.

"Any further reduction in the defence budget would fall on the level of activity that we were able to carry out -- the idea that expensively bought equipment may not be able to be used, expensively employed troops may not be able to be exercised and trained as regularly as they need to be.

"We have maintained... a remarkably high proportion of our military capability while taking out substantial amounts of cost. We can't go on doing that, with further reductions, without having significant impact on military capability.

"If we are going to get control of public spending on a sustainable basis, we are going to have to do more to tackle the growth in the welfare budget."

Hammond's comments are likely to be welcomed in the Conservative Party, whose backbenchers have urged their leader Prime Minister David Cameron to return to traditional Tory values after coming third in a parliamentary by-election last week in a key target seat.

However, they could ignite tensions with the Conservatives' junior coalition partners the Liberal Democrats, who oppose deep welfare cuts.