The Independent Commission for Aid Impact – which scrutinises taxpayer-funded British aid –  said the aid programme has better tools for promoting economic development today than in 2015, but these remain untested.

The body cautions in a report that the government’s intention to use aid to pursue UK national interests does not conflict with good development practice, but it should build long-term opportunities rather than aim for short-term advantages.

Richard Gledhill, the ICAI commissioner who led work on the report, said: “Our reviews have highlighted much for the UK to be proud of. At its best UK aid is world leading.

“But our scrutiny has also shone a light on weaknesses and failures, and some recurring concerns.

“In particular, the dramatic scale up of spend in departments and funds other than DfID [Department for International Development] has often come before the systems, processes and capabilities necessary to ensure the impact and value for money of this spend had been put in place.”

In its report, The current state of UK aid: A synthesis of ICAI findings from 2015 to 2019, the watchdog welcomed DfID’s commitment to the “leave no one behind” principle at the heart of the United Nation’s 2030 Agenda to achieve the Sustainable Development Goals.

This aims to tackle the lack of choices and opportunities required to benefit from development progress that is experienced by some marginalised groups.

ICAI found that the practical implications of DfID’s embrace of this principle had been challenging, but noted “good progress” in addressing these.

However, it noted that a redistribution of the aid budget between departments favouring large middle-income countries – driven by security, climate change or economic goals – risks a reduced focus on poverty and the “leaving no one behind” agenda.

The commission said UK aid has demonstrated that it can deliver in the midst of conflict in some of the world’s most challenging contexts, but needs to do more to address the causes of conflict and fragility.

It calls on policymakers to articulate the rules and principles underlying UK aid better, adding that the country’s standing as a “development superpower” rests not just on the size of its programme, but its integrity.