Several thousand Sikhs marched through central London to protest against the attack by Indian Army at Akal Takhat, Darbar Sahib complex and various other Sikh gurdwaras in June 1984.
Crowds from across the UK gathered in Hyde Park on Sunday and marched to Trafalgar Square, demanding that the June 1984 assault be recognised as a genocide.
The British Sikhs said that India did not do enough to prevent the killing of thousands of Sikhs in riots that erupted later that year.
The UK government’s recent declassification of previously secret papers which showed that an SAS officer was recruited to help plan the operation has also provoked anger among British Sikhs.
“Thousands were killed or disappeared,” Balvinder Kaur of the Sikh Council UK said. “Their families to this date do not know of their whereabouts.”
Claire Fuller, a spokeswoman for the Global Minorities Alliance, said: “The Sikh population in India has been persecuted for centuries. Many see the 1984 massacre as a genocidal attack on their religion rather than an assault on militants, as the official Indian government story states.
“The Indian army killed indiscriminately and without warning, desecrating the temple and killing men, women and children.
“Sacred scriptures which Sikhs consider alive, as the holiest of their religious items, were filled with bullet holes and destroyed. To this day, the event deeply affects Sikhs in the Punjab region and worldwide.”