While paying homage at the Jallianwala Bagh memorial, Welby said, "I cannot speak for the British Government. I am not the official of the government but can speak in the name of Christ. It is a place for sin and redemption. You have remembered what they have done and their memory will live."
"I am ashamed and sorry for the impact of the crime committed here. As a religious leader, I mourn the tragedy", Welby said.
"Here I come only seeking in sorrow and repentance before the people who have suffered in the hands of British bullets. Again I cannot speak for the government but I speak with repentance," he added.
The Jallianwala Bagh massacre took place on April 13, 1919, when troops of the British Indian Army under the command of Colonel Reginald Dyer fired machine guns into a crowd of unarmed protesters and pilgrims who had gathered in Jallianwala Bagh in Punjab's Amritsar on the occasion of Baisakhi.
The crowd had assembled peacefully at the venue to condemn the arrest of two national leaders - Satya Pal and Saifuddin Kitchlew -- when they were fired at indiscriminately by General Dyer and his men.
Hundred years on, the United Kingdom is yet to give a full apology for the gruesome attack on unarmed protesters in Amritsar in 1919.
Earlier this year, former British Prime Minister Theresa May had said that the United Kingdom "deeply regrets" the 1919 massacre and called it a "shameful scar" on the British-Indian history.