The fashion designer Khalid Al Qasimi has died, it has been announced. He was the crown prince and second son of Sheikh Dr Sultan bin Muhammad Al Qasimi, the ruler of Sharjah in the United Arab Emirates, where a three-day period of mourning has been decreed with flags ordered to fly at half-mast. Details surrounding the cause of death were not officially disclosed.

The designer, also known as Sheikh Khalid bin Sultan Al Qasimi, showed his spring/summer 2020 collection for his eponymous brand, Qasimi, on the London fashion week men’s showcase three weeks ago to critical acclaim. The 39-year-old designer was a graduate in architecture and fashion design from Central Saint Martins in London and presented his first collection, which was launched in collaboration with the designer Elliott James Frieze, in the capital in 2008.

A UAE’s presidential affairs ministry released a statement saying: “President His Highness Sheikh Khalifa bin Zayed Al Nahyan mourns with grief and sorrow, the death of Sheikh Khalid bin Sultan bin Mohammed Al Qasimi, the son of the ruler of Sharjah, praying to Allah the Almighty to rest his soul in peace, and grant his family patience and solace.”

His death comes 20 years after his older brother, Sheikh Mohammed bin Sultan bin Mohammed Al Qasimi, died from a drug overdose at the age of 24 at the family’s home in East Grinstead in 1999.

The CEO of the British Fashion Council, Caroline Rush, told WWD: “Khalid Qasimi was a talented young designer whose collections were modern, elegant and forward thinking. Our thoughts are with his family, friends and colleagues.”

Last week, Qasimi was involved in a disagreement over a T-shirt design from his autumn/winter 2017 collection that was replicated by the brand Vetements on its spring/summer 2020 catwalk in Paris. The T-shirt, which read “Don’t shoot” in Arabic, French and English, was a semi-replica of one originally worn by journalists in Lebanon during the Israeli invasion of the country in 1982.

Qasmi, who did not own copyright for the phrase, told Vogue Arabia: “I understand what they are doing. It’s about consumerism. But it’s a complete F-U to the region … I used that print to highlight the plight of something going on in the Middle East. For Vetements to use it in such a flippant and provocative manner; I don’t think they realise what these words mean to us Arabs.”