A letter from a survivor of the Nazi extermination camp in Sobibor has been discovered 75 years after the war by Amsterdam’s Resistance Museum.

The letter by Jules Schelvis to his cousin Karel Stroz, dated May 7, 1945, is the earliest evidence from a Dutch survivor of the existence of Sobibor, which was razed to the ground by the Nazis in 1943 following a prisoners’ uprising.

An estimated 180,000 predominantly Jewish prisoners, 33,000 of them from the Netherlands, were murdered in the camp near Lublin in Poland. Just 18 Dutch detainees survived, including Schelvis, who dedicated the rest of his life to ensuring the horrors of the camp were not forgotten. He died in 2016, aged 95.

In the letter, he wrote: ‘Gretha, David, Hella, Chel and Herman were, I am 99 per cent sure, gassed immediately on arriving at SS special camp Sobibor, near Lublin.

‘It will be painful for you to read all of this, but I have to tell you nonetheless.’

The letter, still sealed, was bequeathed to the Resistance Museum and discovered by researcher Jos Sinnema. Schelvis wrote it in Vaihingen hospital, near Stuttgart, in the final days of the war, and gave it to another camp survivor who was on his way back to the Netherlands, but for reasons that are unclear it never arrived.

‘I fell off my chair,’ said Sinnema of his reaction to opening the envelope. ‘It felt like a time capsule, something you open after it’s been closed for a very long time.

‘This is something the family were supposed to receive. It feels very special, but at the same time onerous, because you’re the first person to read something that wasn’t meant for you.’

Sinnema was able to deliver the letter to Stroz, who still lives in Amsterdam, after 75 years. Stroz said it was likely that the man asked to deliver it, Nico Staal, had been unable to find him in the chaotic weeks after the war. ‘There were no trams and people were in poor health. Staal would have had to walk a very long way to deliver the letter,’ he told NOS.