International donors are being urged to be more transparent about how corruption affects their aid programmes as a new report estimates that practices such as bribes, theft and embezzlement cost the world $500 billion a year.

An analysis of the available data on corruption in health care, carried out by campaign group Transparency International, describes such practices as an "ignored pandemic".

The report focuses on corruption perpetrated by frontline health workers with practices including accepting bribes, stealing medicines to resell them and moonlighting in other jobs while being paid by public health services.

The report estimates that seven per cent of health expenditure is lost to corruption and, with annual global health spending now in excess of $7.5 trillion a year, this equates to more than $500bn a year.

The analysis also warns that it leads to 140,000 child deaths every year, is a driver of anti-microbial resistance and also hampers efforts to reduce rates of HIV transmission.

While the report highlights corruption carried out by health workers the researchers say this is often driven by deeper structural problems “beyond the control of underpaid and overworked frontline service providers”.