London’s Mayor Sadiq Khan on Wednesday said that the United Kingdom government should make a formal apology for the 1919 Jallianwala Bagh massacre, in which nearly 400 Indians were shot dead by British soldiers on the orders of General Reginald Dyer, Reuters reported.

“It is wrong that successive British governments have fallen short of delivering a formal apology to the families of those who were killed,” Khan said during a visit to the Golden Temple in Amritsar. “I am clear that the government should now apologise, especially as we reach the centenary of the massacre. This is about properly acknowledging what happened here and giving the people of Amritsar and India the closure they need through a formal apology.”

Khan called the massacre one of the most horrific events in Indian history. “The tragedy in 1919 on the eve of Vaisakhi [festival] is one we must never forget,” the mayor of London wrote in the visitors’ diary at the Golden Temple, PTI reported.

Former UK Prime Minister David Cameron had described the events at Jallianwala Bagh in 1919 as “a deeply shameful event in British history,” when he visited the Golden Temple in 2013. “We must never forget what happened here and we must ensure that the UK stands up for the right of peaceful protests,” he added. However, Cameron stopped short of issuing a formal apology.