A “success cartel” of major donor agencies, including the UK government, is exaggerating its impact in the world’s poorest countries, hundreds of researchers have warned.

Writing in the journal BMJ global health, academics raised serious concerns about the independence of evaluations into global health and development projects, and called for greater safeguards to stop powerful bodies from influencing results.

Most aid and development projects are subject to independent evaluations. But the article warned that funders maintain a high degree of confidentiality and control over the results.

In some instances, researchers who attempted to document negative findings had been subject to “personal and institutional pressure, intimidation and censorship”, the article said. The authors also warned of more subtle forms of bias, such as self-censorship on the part of academics and embellished findings.

“It undermines learning,” said Katerini Storeng, associate professor at the Centre for Development and the Environment at the University of Oslo, and the lead author. “If we’re not forthright about the limitations of what is being implemented or the strategies that we’re pursuing it becomes difficult to learn anything.”

She added that communities who are being served by health projects could also potentially suffer.

A registry for global health evaluations, similar to the one promoting transparency in clinical trials, is among the article’s recommendations, which are endorsed by more than 200 researchers based in 40 different countries.

“It is well known in clinical medicine that pharmaceutical industry-funded trials are more likely to produce positive, flattering results than independently funded trials,” the authors said. “It is time to debate this important issue in global health too.”

Perverse incentives across the development sector encourage the use of “bad or fudged” data by agencies, it added. The article referred to previous warnings of a “success cartel” in global health, where pressure to achieve targets has led some governments and other development agencies to inflate their achievements.

Cuts to research budgets in global health have left universities increasingly reliant on funding from government departments, private foundations and industry.

The article says researchers often receive funding from donors , including the UK, US and French governments, as well as the international health body Unitaid, and the Bill & Melinda Gates Foundation. Such bodies commission academics to evaluate programmes they are funding, the researchers warn, “even though they have a stake in results that demonstrate the success of a multibillion-dollar investment”.

The researchers raised concern over rules imposed on them by the UK government’s Department for International Development (DfID), which state they must not embarrass the department, or bring it into disrepute.

In a statement, DfID said the clause “does not have the intention or effect of gagging any party, nor of preventing whistleblowing, which would be unlawful, and it does not prevent criticism of DfID’s policy”.

Donors, the editorial argued, should scrap such clauses and make it clear to NGO partners that they cannot interfere with the design, data collection analysis or sharing of findings. The recommendations also called on universities to refuse contracts that prevent researchers from sharing critical findings.

Each study should also be overseen by an independent research oversight committee, which includes representatives from the communities that are being studied or civil society organisations, researchers added.

The article was prompted by a recent paper in the Lancet, in which academics reported they had been subject to censorship when evaluating a maternal health project funded by the DfID – a claim the department denied.

DfID said it was committed to supporting rigorous research: “DfID takes issues of research ethics, independence, quality and transparency seriously. We have procedures in place that we require projects and programmes we work with to adhere to.”

It added that contract clauses are designed to protect DfID by ensuring that contractors adhere to “good working practices and do not engage in activities that bring DfID into disrepute”.

A spokesperson for USAid said the agency had noted the editorial, adding: “USAid is committed to the pursuit of high-quality evaluative activities that support data-driven decision-making.”