Relatives of the man accused of running Syria's chemical weapons programme have reportedly been granted British citizenship.
Amr Armanazi directs the Syrian Scientific Studies Research Centre (SSRC) and has been involved in the Syrian government's production of sarin gas, according the US government.
Sarin is believed to be the nerve agent used against civilians in Khan Sheikhoun. At least 80 people died in the attack in Idlib province, including 33 children.
But despite Armanazi having been subject to US sanctions since 2012, and later being added to European and UK blacklists, his son and his brother have been allowed to become British nationals, the Sunday Times reported.
Armanazi's youngest son, Bisher Armanazi, reportedly works with his elder brother, Zeyd Armanazi, at a London investment bank. Zeyd Armanazi has been a British citizen since 2009, the Times said – before the Syrian civil war began and his father was added to sanctions lists.
Their uncle, Ghayth Armanazi, was also given a British passport.
The newspaper said Amr Armanazi's British family denied he is involved in military research and called the Khan Shikhoun attack a "heinous crime".
But Armanazi was placed under US sanctions for his leadership of the SSRC. According to a US Treasury announcement of the sanctions, the SSRC has a nominal civilian function but its activities "focus on the development of biological weapons, chemical weapons, and missiles".
The statement added: "During his tenure, Armanazi oversaw a facility that was involved in the production of sarin nerve agent."
This facility is believed to be a compound at al-Safir, near Aleppo. According to Foreign Policy, the SSRC is also involved in developing the chlorine filled barrel bombs that have been used since 2014.
A profile of Armanazi written by industry magazine Israel Defence in 2013 claimed he has extensive familial links with Bashar al-Assad. The pair met each other while working at the Syrian Computer Society in the 1990s, the magazine said, and that Armanazi enjoys a status similar to that of a senior government minister because of the importance of his work.
One of the most significant chemical weapons attacks in Syria took place in March 2013, when at least 1,000 people were killed by sarin in the Ghouta area of Damascus.
Later that year, US officials said Armanazi was not directly involved but the SSRC were responsible for the development of the weapons used.
The event was considered a turning point for US involvement in the Syrian conflict. Barack Obama had said the use of chemical weapons was a "red line" but failed to enforce it.
President Donald Trump responded to last week's smaller chemical attack by firing 59 cruise missiles at a Syrian government airbase.
A Home Office spokesperson told IBTimes UK they did not comment on individual citizenship cases.