Chemical weapons experts have called for an international inquiry into allegations that Sudan's military has developed chlorine bombs, after reports of their use in the civil war.
Former investigators have told The National that material examined in a media probe appeared consistent with a rudimentary chemical weapons programme.
They stressed the urgency for an investigation by the Organisation for the Prohibition of Chemical Weapons (OPCW) into allegations that the Sudanese Armed Forces (SAF) developed and used chlorine-filled munitions.
The allegations were detailed by The Washington Post after it examined videos, documents, photographs and messages, which indicated a secret Sudanese chemical weapons programme, including the manufacture and testing of chlorine bombs. There is also evidence that the SAF, led by Gen Abdel Fattah Al Burhan, used chemical weapons in attacks in 2024 and 2025, dropped by its Su-24 bombers.
The civil war erupted in April 2023 during a power struggle between the SAF and the paramilitary Rapid Support Forces (RSF). Gen Al Burhan has vowed to continue fighting until the RSF is defeated, rejecting repeated attempts by the US and regional powers to broker a ceasefire. Both forces have been accused of grave abuse during the conflict.
Philip Ingram, who spent 26 years in British military intelligence and was a specialist in chemical and nuclear weapons, said the SAF could have constructed a rudimentary programme
The material it obtained could be made into a weapon relatively easily. “All you need is a canister that can hold the gas under pressure," he said. "Then you just need an explosive device to make it detonate.”
Sudanese officials would also know its limitations, particularly in Sudan's hot climate where the toxins would have been rapidly dispersed.
The OPCW has disclosed to The National that several countries have made a formal request “to obtain clarification from Sudan regarding allegations of chemical weapons use”.
Dr Gareth Williams, a former senior OPCW official, said the material he had examined was “troubling” and “would warrant further investigation because it looks on the surface like a chemical weapons programme”.
“We can see fabrication and adaptation of gas canisters for delivery as munitions,” he told The National. “So that's significant because it's a breach of the Chemical Weapons Convention [CWC] straight away, the manufacture of something intended to disperse a toxic gas.”
‘Troubling’ evidence
Lennie Phillips, a former OPCW investigator who worked on the destruction of Russia's chemical weapons programme after the Cold War, was shown the evidence.
“This could quite conceivably be a chemical weapons programme, with the use of chlorine as a chemical weapon, but there was insufficient information as to whether it had actually been used,” he said.
Video footage he had seen appeared to show an ability to fill a canister. “We saw these bombs with a mechanism that could be used to break open the canisters,” he said. “It was all consistent with a chemical weapons programme.”
Mr Phillips, who was on the OPCW team in Syria that monitored the destruction of Bashar Al Assad’s declared chemical weapons, said investigators would need to interview people who had been present during any alleged attack and establish what they “felt, smelt and saw”.
Dr Williams, who worked as a scientist at Britain's renowned Porton Down chemical and biological defence laboratory, said photographs from the reports showed the “characteristic colour of chlorine, which is yellowy-green”.
He said there was evidence of what appeared to be a rudimentary cylinder-filling facility, involving the transfer of material from larger barrels into smaller containers.
It has been reported that other former OPCW officials spoke to eight witnesses in Nairobi, Kenya, where thousands of Sudanese refugees had fled to escape the continuing war. They said witnesses were able to provide “a number of credible incidents involving unexplained illness following military activity”.
Easy to make
Chlorine is a widely available industrial chemical largely used for household water, making it relatively easy to obtain compared to more sophisticated chemical warfare agents.
Western intelligence agencies, including the CIA, MI6 and French intelligence service DGSE, would be examining the claims, Mr Ingram said.
“One of their top intelligence-collection priorities is nuclear and chemical, basically anything that can be classed as weapon of mass destruction proliferation around the world, so they’ll be looking at the credibility behind these reports.”
Chemical investigation
The allegations now present the OPCW and its member states with a question of whether enough evidence exists to trigger a formal inquiry.
Since 1999, Sudan has been signed up to the CWC, which prohibits the development, stockpiling and use of chemical weapons.
An investigation can be triggered by a request from any signatory for an Article IX “challenge inspection” that includes an on-site visit when there are concerns about potential non-compliance.
The request must contain information supporting the concern, after which the OPCW's director general begins preparations for an inspection at short notice if the request meets the requirements. Under the rules, Sudan would not be able to simply to refuse it.
The OPCW said the clarification process was ongoing and noted that having signed up to the CWC, Sudan agreed “never to develop, produce, stockpile, transfer, or use chemical weapons”.
“OPCW's Technical Secretariat continues to monitor the situation in Sudan closely and is ready to offer further support, should it be formally requested,” it added in a statement to The National.
“The OPCW needs a mandate and that mandate can only come from the member states,” Dr Williams said. “It's up to countries to push this and make it an issue in the policy-making organs in the OPCW.”
Sources have also suggested that Washington might press the Sudanese government to conduct an investigation, admit to the programme, then destroy the weapons and “give the White House a PR win”.
‘Poor man’s weapon’
Col Hamish de Bretton-Gordon, a former British Army chemical warfare specialist who worked covertly in Syria to obtain samples from chemical attacks for the International Criminal Court, said the evidence clearly indicated chlorine being weaponised.
“Chemical weapons are a poor man's nuclear weapon and they are morbidly effective, dead easy to use,” he said. “[Bashar Al] Assad stayed in power for 11 years using industrial amounts of chlorine in Syria and on the evidence presented the SAF most likely made a decision to go for it with chlorine.”
Chlorine is particularly dangerous against civilians sheltering in enclosed spaces, he said. “It's a choking agent that destroys your lungs, so you can't breathe. It's a terrible thing and against civilians, particularly in confined spaces below ground, it's incredibly effective at killing people.”
