Westminster has barred the Scottish Government from joining a UK delegation to a vital international summit this month aimed at combating poverty, injustice, inequality and climate change.

The UK Secretary of State for International Development, Justine Greening, rejected a request from the Scottish minister, Humza Yousaf, to join the official delegation to a United Nations (UN) meeting of world leaders to adopt 17 sustainable development goals.

Greening said that the delegation was full of UK ministers and officials so there was no space for Yousaf - who responded by saying it was a “disgrace” that Scotland was being snubbed.

The summit in New York on September 25-27 is expected to be attended by over 150 world leaders. According to the UN, they will commit to achieving three “extraordinary things” in the next 15 years.

“End extreme poverty. Fight inequality and injustice. Fix climate change,” the UN said. “The global goals for sustainable development could get these things done, in all countries, for all people.”

The new goals are designed to replace the UN’s eight millennium development goals, agreed in 2000. Though they didn’t eradicate poverty and hunger, they are seen by the UK government as “largely a success” because they led to dramatic improvements in living standards around the globe.

The new sustainable development goals include targets to “achieve gender equality and empower all women and girls” and to “reduce inequality within and among countries”. They call for “urgent action” on climate change, the conservation of the oceans and a halt to the loss of wildlife.

The First Minister, Nicola Sturgeon, announced in July that Scotland would be one of the first countries in the world to sign up to the new goals. At the time, the UN Institute for Training and Research praised “her commitment to the future of our planet.”

Yousaf, the Scottish Minister for Europe and International Development, wrote to Greening in June stressing Scotland’s record on international development, including its partnership with Malawi. He asked to join the UK delegation to the New York summit, arguing this would be “a good story for both our governments.”

But Greening’s assistant private secretary, Camilla Nickless, replied on the September 8 turning down his request. “We regret to inform you however that Mr Yousaf will not be able to attend as part of the UK delegation on this occasion,” she said.

“There is a limit on the overall size of the UK delegation for the summit, with places allocated to principal ministers and senior officials required to drive forward UK policy plus support staff running UK hosted events. You will also be aware that international development is a reserved matter under the devolution settlement.”

The rejection angered Yousaf. “It is a disgrace that the Tories have frozen Scotland out of these crucial UN talks on tackling global poverty,” he told the Sunday Herald.

“Scotland has a long and proud record on international development, tackling climate change and raising issues of climate justice. Our voice would have both expressed that experience but also been a strong voice for international action on these issues,” he said.

“Scotland has in recent years been part of the UK delegation to the annual UN climate talks so it is not unreasonable that on an area as important as tackling global poverty and the new sustainable development goals, that Scotland should be part of the UK delegation to the United Nations.”

Robert Anderson, who chairs the Scotland Malawi Foundation and has 30 years experience in international development, described Greening’s decision as “politically-driven and small-minded”. It will not foster the good relations that he had worked for between the UK and Scottish governments, he argued.

“The Scottish Government has made a tremendous additional voluntary contribution to international development,” Anderson said. “So why not make space for one or two from Scotland within what will be a sizeable delegation from the UK?”

The Department for International Development in London declined to say how many UK ministers and officials would make up the delegation, quoting security reasons. It reiterated that international development was a matter reserved to Westminster.

A UK government spokesman said: “We will represent the views of the whole of the UK, including the Scottish people, at the UN Summit in New York to adopt the new global goals. We are pleased the UK and Scottish governments are united on the importance of the new global goals and we have consulted regularly with organisations in Scotland.”