One of Britain’s most eminent former diplomats has described the country as a fading power, saying that cuts to the Foreign Office have undermined its standing on the world stage.

As the UN security council celebrates its 70th birthday on Sunday, Sir Jeremy Greenstock, chair of the United Nations Association - UK and a former British ambassador to the UN, said this and the previous government had shown a worrying lack of concern for foreign affairs, which had hurt Britain’s standing abroad.

“It has always been in the traditions of the UK to be part of the search for global solutions. I don’t get the same feeling from the last government or this government. Immediate domestic concerns are coming first and foremost.

“We are not so much a power any more, our relative power has faded, put us into the shade. The Foreign Office is constantly being cut, our military being cut,” he said. “The number of armed forces has gone down, our contribution to peacekeeping is negligible, we haven’t succeeded in our interventions in Iraq, in Afghanistan.”

Greenstock served at the UN as Britain’s special representative from 1998 to 2003 – during the conflicts in Afghanistan and Iraq – and was then special representative in Iraq until 2004.

Sir Jeremy detects ‘increasing scorn for the quantity’ of Britain’s contribution in Iraq and Afghanistan. Photograph: Odd Andersen/AFP/Getty Images

“There is increasing scorn for the quantity of what we put in there. When I was in Iraq the UK had 50% of the responsibility within the US coalition but we put in 2% to 3% of the resources; the Americans put in 95%. Of course, the Americans came to regard this as irrelevant in the end. That all affects our standing.

“I think the British people are going to regret that we are much more focused currently on the week-to-week and the strategic trends are not discussed. Ministers aren’t interested, they’re so overwhelmed by the weight of domestic problems, and there is this sense that the world is moving too fast for leadership to grasp and retain a strategic vision.

“We’re not giving our governments space for the long term. They can’t move without being criticised. That’s why the UN shouldn’t be scorned for not solving every problem.”

Greenstock gave credit to the UK for being one of only two countries in the world that holds fast to spending 0.7% of GDP on foreign aid, but said our commitment to UN peacekeeping was paltry.

“We are team workers, very effective behind the scenes. We get credit for that. But the resources we have to bring to the solutions of problems have faded dramatically.

“The UK is very wise but has no power, and the US is very powerful but has no wisdom,” he said. “Of course, neither of those statements is entirely true, no country has both, but the UK once had the best balance until our public coffers began to be reduced to the point that we no longer have the resources.”

The security council, formed in 1946, is the United Nations’ most powerful body, with “primary responsibility for the maintenance of international peace and security”. Five countries sit as “permanent members” along with 10 elected members with two-year terms.

Greenstock said he thought the UN security council had been remarkably successful in damping down interstate wars. “In my view in a number of instances it’s done very well, but it’s always the case that where the most difficult issues are is where the security council has been most powerless to act.”

He said he found it hard to imagine that the next 70 years would see Britain holding its permanent place on the security council alongside Russia, China, France and the US. The institution has faced heavy criticism for what is seen as an outdated and skewed tier-system from which dozens of countries are excluded.

“I don’t think the powerful states can get away with denying transparency and fair process at the UN for very much longer. Many global citizens wish for moral leadership on fair distributions of wealth, climate change, peace and security.”

He defended the successes of the security council. “The UN security council has a budget the same size as, what, a city the size of Birmingham? It’s not a large budget to solve the world’s problems. The reluctance of voters and parliament to pay large sums to the key work that needs to be done in our national interests, and in the interests of international security and in humanitarian interests, is a problem.

“Unless there is a large threat, like a Mars invasion, which actually climate change is the equivalent of, then people now remain occupied with the small-scale – they would rather save their local hospital ward than save the Maldives.”

Matthew Rycroft, Britain’s current UN ambassador. Photograph: Bebeto Matthews/AP

The current British ambassador to the UN, Matthew Rycroft, insisted that Britain remains a “big player, as befits a country of our size and standing and capability. We are a strong voice on all the issues the UN acts on, especially peace and security, international development, and humanitarian issues.

“The UK is not scorned at the UN. But our responsibilities do come with baggage. So we are very careful to use our permanent membership of the SC carefully – for example, we haven’t vetoed since 1989 – and to demonstrate through our activism that we can be a force for good at the UN and around the world.”

• This article was amended on 19 January 2016 to restore Sir Jeremy Greenstock’s current job title as chair of the United Nations Association - UK.

