Only a quarter of the 59 labs that handle the world's deadliest pathogens have top-level biosecurity, experts warn. They fear lax rules could lead to another pandemic.

• There are 59 biosafety level 4 labs (BSL-4) in the world, but only a few scored high on safety.
• A new report revealed only a quarter of countries with these labs have high biosecurity scores.
• The labs are where researchers work with the most dangerous pathogens on the planet.

Only around a quarter of countries with biosafety level 4 labs - where researchers work with the world's deadliest pathogens - have high biosecurity scores, according to a new report.

As US intelligence agencies are investigating the possibility that COVID-19 leaked from China's Wuhan Institute of Virology, more questions are being raised about the safety and security of similar such labs around the world.

Gregory Koblentz, an associate professor of biodefence at George Mason University, and Filippa Lentzos at King's College London recently mapped out all of these facilities using open-source research. Their findings can be found here.

Read more: How DNA-testing startup Helix became one of the nation's leading coronavirus tracking labs

According to their report, there are at least 59 maximum BSL-4 labs that are currently in operation, under construction, or planned around the world. They span 23 countries, including the UK, US, China, and India.

The largest concentration of BSL-4 labs is in Europe (25) while North America and Asia have roughly equal numbers, with 14 and 13 respectively. Three-quarters of the labs are based in urban centers.

But only about one-quarter of the countries with BSL-4 labs received high scores for biosafety and biosecurity as measured by the Global Health Security Index, the report found.

"Our study also revealed that there was significant room for improvement in the policies in place to ensure that these labs were operated safely, securely and responsibly," Koblentz and Lentzos wrote in the Guardian.

"The vast majority of countries with BSL-4 labs do not conduct oversight of the type of gain-of-function research that has been a central feature in the debate on COVID-19's origin, as potentially responsible for the possible leak from the Wuhan Institute of Virology," they added.

The report has some experts worried that lax controls and regulations at some locations could lead to another pandemic.

"The larger the number of institutions and the larger the number of individuals with access to these dangerous agents, the greater the risk," Richard Ebright, a professor of chemical biology at Rutgers University, told the Financial Times. "Accidents and leaks already happen in very large numbers, especially in places that have weaker biosafety standards."

"We need to strengthen biosafety and biosecurity rules around the world" Ebright added.

BSL-4 labs are built so that researchers can safely work with pathogens that can cause serious diseases and for which no treatment or vaccine exists. Researchers working there are highly trained and must wear personal protective equipment.

To date, more than 176 million cases of coronavirus have been reported worldwide, according to a tracker by Johns Hopkins University. More than 3.8 million people have died.