Faced with growing demand for an apology, Prime Minister Theresa May on Wednesday reiterated the UK government’s long-standing expression of ‘deep regret’ over the April 1919 Jallianwala Bagh massacre, calling it a ‘shameful scar’ on British Indian history.

An apology on behalf of the state is usually made by the prime minister. Mark Field, junior minister in the foreign office, told MPs seeking the apology on Tuesday that it was not for him to tender it, but said the issue is a ‘work in progress’.

Corbyn said: “I am very pleased that the prime minister mentioned what happened in Jallianwala Bagh and the issues of the massacre at Amritsar a hundred years ago. I think the people in memory of those that lost their lives and the brutality of what happened deserve a full, clear and unequivocal apology for what took place on that occasion”.

In a brief statement during Prime Minister’s Questions in the House of Commons, May said: “The tragedy of Jallianwala Bagh in 1919 is a shameful scar on British Indian history. As her majesty the Queen said before visiting Jallianwala Bagh in 1997, it is a distressing example of our past history with India”.

May went on to extol what she called the “enormous contribution” of the Indian diaspora, but did not dwell on the issue further during the session, when Labour leader Jeremy Corbyn called for the apology a hundred years after the incident.

Responding to May’s comments, senior Labour MP Virendra Sharma said: “I appreciate the Prime Minister’s comments today, and thank her for her earnest words, but they are only the beginning of an apology not the full and frank formal apology that the communities affected need.

“I would also like to offer my fullest thanks to Jeremy Corbyn for his words of support, and his commitment to a full apology when he becomes Prime Minister. The wounds of the Jallianwala Bagh Massacre still haunt millions and should be laid to rest at this the centenary of the horrendous act.”

The Jallianwala Bagh massacre has been the subject of several debates since 1919 in the UK parliament, most recently on Tuesday in the Westminster Hall and in February in the House of Lords, when the government said it has been ‘reflecting’ on the apology demand.

Field told MPs: “It is not appropriate for me to make the apology I know many would wish to come. I can assure the house that this is a work in progress. It is an active debate taking place among ministers and among senior officials and our high commissioner in New Delhi.”

The British high commission in New Delhi, Field added, had been asked to visit the memorial site on April 13 and lay a wreath. There will also be a public acknowledgement of the centenary and the sense of ‘deep regret’ in events organised in the UK.

Responding during the PMQs to Conservative MP Shailesh Vara, who wanted May to commend the Indian diaspora for contributing nearly 10 per cent of taxes even though constituting only 4 per cent of the UK population, May said the community deserves to be congratulated.