Spending 2% of GDP on defence is a bare minimum and not a fundraising target to be celebrated reaching, a former UK military chief has warned.

Lord Stirrup, who served as Chief of the Defence Staff from 2006 to 2010, branded current funding for security "woefully inadequate" given the international threats faced.

The independent crossbencher said the 2% spending target for NATO members was meant as a "baseline against which one can measure delinquency" and argued Britain should be spending 3%.

Lord Stirrup issued his stark message during a debate in the House of Lords on the UK's armed forces and the NATO military alliance. On the 2% spending target, he told peers:

"It is a bare minimum designed to provide a clear baseline against which one can measure delinquency. It's not like some fundraising target which we should celebrate reaching."

Lord Stirrup also cautioned Labour that the present Conservative Government was "far from the only one to have used creative accounting when it comes to defence expenditure". He added:

"The UK's commitment to the 2% floor merely raises us above the level of those who should be named and shamed. It does not imply an adequate level of investment in our future security."

"Indeed I would argue our public expenditure on security remains woefully inadequate in light of the present challenges to international order."

Arguing that the military was "spread too thin", Lord Stirrup said:

"We ought to be spending more like 3% of GDP on defence, not just the minimum of 2%."

He said: "Successive governments have paid lip service to the fact that preserving the safety and security of their citizens is their priority.

"But their actions, particularly in spending decisions, have said otherwise."

He acknowledged the government had "reversed the miserable downward trend of investment" in recent years, but said it must do more. He added:

"We can and should set the example for others. It's clearly in our interests to do so."

Opening the debate, defence minister Earl Howe said nearly seven decades after its formation, NATO "remains as relevant as ever", which was why the UK continued to meet the 2% GDP target.

He added: "However, the alliance is only as strong as its weakest link.

"It's not enough for us to pull out all the stops, we need other nations to up their game."

He argued US President Donald Trump had been right in his demand that "it was time for the allies to pay their way".