A Holocaust survivor has warned Britons to be vigilant against antisemitism as the country remembers the genocide of six million Jews on Holocaust Memorial Day.

John Dobai, 89, lived through the Second World War as a child in Budapest, Hungary, but five of his family members were killed – two grandfathers, two aunts and a cousin, who was just 17.

Mr Dobai has lived in Britain since 1948 and, speaking from his home in Kew, west London, he told the PA News Agency that antisemitism is as prominent in modern Britain as it has ever been.

He said: “I have lived in this house for over 60 years and for 59 years I did not see any sign of antisemitism.

“But in the last 12 to 18 months we had graffiti on benches along the towpath saying ‘Holocaust: six million lies’ and similar graffiti on walls and benches in the neighbourhood.

“Some people I have met in this area have also declared that ‘people from north London are very difficult’.

“In my talks I conclude by calling on the audience to become witnesses and, if they see examples of racial discrimination, not to be silent. To deny any racial slur – whether it’s against people of colour or other belief systems – and to speak up.”

Raised as a Catholic only child by parents of Jewish descent, Mr Dobai’s father was separated from the family and sent to a forced labour camp during the Second World War.

In 1944, Germany invaded Hungary after it learned of secret attempts to make peace with the Allies and quickly introduced harsh antisemitic policies.

All Jews in Budapest were forced to live in ghettos, wore yellow stars of David on their clothes and could not go to school.

“I was sent out by mother to buy something from the shops,” Mr Dobai remembers. “On the way I met a classmate and I said to him, ‘I’m looking forward to going back to school’. And he said he had been told he was going back to school but I was not because I was ‘a dirty, stinking Jew’.

“I protested that I was Roman Catholic and he repeated the ‘dirty, stinking Jew’. I went home crying and my mother had to explain to me that in fact I came from a Jewish family. This was a tremendous shock.”

When his mother’s letters to rural family members kept being returned unopened, she realised rumours of genocide were true – and soon after this the Nazis started to round up Budapest’s Jews for deportation to the death camps.

Mr Dobai said: “We were told to form up a column in front of the house to be taken to a relatively nearby railway station. But on the way some administrative problem arose and we were pushed into an empty apartment, about 25 people to a room.

“When I was in this column, a man came up to me and said, ‘I hope you die’. This was a tremendous shock because I didn’t know the man, I had never met him and never spoke to him. How could he have such hate towards us?”

As the Soviets advanced on Hungary’s frontiers, Mr Dobai’s father was released from the forced labour camp and returned to Budapest, where he was one of many Jews who acquired papers from Swedish diplomat Raoul Wallenberg allowing them to move into a protected safehouse.

Between 25,000 and 100,000 lives are believed to have been saved by Mr Wallenberg’s actions during the war.

But Mr Dobai was not safe yet. As the Soviets neared Budapest, the Germans and Hungarian fascists commenced a brutal campaign of killings against the 60,000 Jews living in the “international ghetto” of safehouses.

“The Nazis were emptying houses, taking people down to the Danube and tying three people together,” he recalls. “They would shoot the centre one so the dead body would drag the other two down into the river.

“I remember looking out of the flat we were in and Jews being led towards the Danube and then about 10 minutes later hearing the rattle of machine guns.

“And then the fascists would come back. I remember that they were carrying the machine guns wrapped in sacking because the barrels were still hot.”

Mr Dobai’s grandparents were two of 45,000 Jews massacred in this way, and he and his parents were only saved when the Soviets took control of the city before the killings were complete.

After emigrating to Britain in 1948, Mr Dobai finished school, attended Durham University and raised two children with his wife Joan, who died last year.

Since retiring in 1998, he has given more than 180 talks about his experiences, including in schools and colleges, working with the Holocaust Educational Trust.

He said: “It is an opportunity for me to remember those people who were murdered, the only reason being that Germany and Hungary declared them to be enemies of their countries.

“They were innocent of all criminal or any other proclivity against the state. They were murdered because those countries decided that the happiness of Germans and Austrians and Hungarians depended on the total destruction of Jews.

“The second reason is I want to show that racial or colour discrimination can lead to severe discord within society.”

Karen Pollock, chief executive of the Holocaust Educational Trust, said: “Today we mark Holocaust Memorial Day on the 78th anniversary of the liberation of the former Nazi concentration and death camp, Auschwitz-Birkenau.”

She added: “We also pay tribute to the incredible survivors, many of whom still share their testimony day in and day out to ensure that future generations never forget the horrors of the past.”