The foreign secretary is set to reveal which UK projects around the world will be axed or reduced following a decision to slash foreign aid spending by almost a third, Sky News understands.

A statement to parliament was scheduled for this week but had to be postponed because of the death of the Duke of Edinburgh, according to two Whitehall sources.

They said a new slot was set for next Thursday, but this has not yet been confirmed by the Foreign, Commonwealth and Development Office and it could yet be further delayed.

“If they change the date now, they are utterly ridiculous,” one source said.

A second source said: “There will be huge, huge cuts in some parts of the world… If you are going to make such a big cut, then I think any government would have to go before parliament.”

Sarah Champion, a Labour MP and chair of the international development committee, is urging the government to rethink the aid squeeze, which comes in a year when the UK seeks to burnish its credentials as an important player on the world stage. Boris Johnson hosts a G7 summit of world leaders in June and a climate change conference in November.

“I have to say that it makes me feel hugely embarrassed,” Ms Champion told Sky News.

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“I think it makes the government look like hypocrites. I don’t know – are they going to get a slow hand clap when they walk into the G7? They’re meant to be the president of it and they are saying: Yes, yes, yes, we are cutting money to the poorest people.”

Mr Johnson’s government last year confirmed it would breach its own manifesto pledge by reducing “temporarily” to 0.5 per cent from 0.7% the amount of national income spent on foreign aid because of the economic hit caused by the coronavirus pandemic.

A contraction in the economy means overseas aid spending will be around £10bn this year compared with £14.5bn in 2020.

Ms Champion said she will be asking Dominic Raab for clarity on the aid cuts announcement when he faces routine MPs’ questions on Tuesday.

The foreign secretary is also due to appear before her committee on Thursday.

“What I want to see is for the foreign secretary to come to the dispatch box and explain his decisions,” she said.

“What I don’t want to see is a written statement squirrelled out when everyone’s attention is somewhere else just because they don’t want to deal with the consequences of their political decisions. That is the coward’s way out.”

Diplomats and ministers are acutely aware of the outcry they will trigger when details are finally released about what is being cut and where. They already felt significant heat over reduced spending on vital programmes to help people from Yemen and Syria.

One diplomatic source said they wanted to use a statement to parliament to set out all the other painful decisions “in a one-er” – to deal with the bad news in one hit.

It is thought that the information, when it finally emerges, will be released as a written statement rather than – as Ms Champion would like – an aural one.

Sir Mark Lowcock, the United Nations’ humanitarian chief, said he hopes the UK will reconsider reducing its aid spending target.

He said this is not just a matter of empathy and kindness but also one of self-interest.

A failure to offer aid to the poorest and most unstable countries inevitably results in increased global instability and less security in the UK.

“The learning point from a year of pandemic is that this is a small planet,” he said in an interview.

“Problems starting in one place reverberate quickly everywhere else. If you want to be safe at home, you have to contribute to stability and fairness abroad as well. If you want to be a leader you can’t lead simply on the basis of your rhetoric. You have to put money where your mouth is.”

The cuts announcement is expected to detail reductions in aid programmes in the Middle East and Africa as well as the culling of initiatives in more prosperous countries across Asia and Latin America.

Spending on programmes linked to climate change is set to be protected. There is also expected to be a shift in how the UK directs its humanitarian assistance, with a closer link between security priorities and less weight being placed on poverty reduction. This could see an increase in funding for security-related assistance programmes in Ukraine, for example.

Asked about plans for an announcement on the impact of the foreign aid cuts, a government spokesperson said: “The UK is a world leader on international development. In 2020 we were the third biggest aid donor globally, spending £14.5bn.

“The seismic impact of the pandemic on the UK economy has forced us to take tough but necessary decisions, including temporarily reducing the overall amount we spend on aid. We will still spend more than £10bn this year to fight poverty, tackle climate change and improve global health.

“We are working through what this means for individual programmes. Decisions will be announced in due course.”