British Prime Minister David Cameron visited the site of one of the British Empire's bloodiest episodes in India on Wednesday (February 20), laying a wreath and expressing regret at northern Amritsar city, scene of a notorious massacre of unarmed civilians.

The 1919 slaughter, known in India as the Jallianwala Bagh massacre, was described by Mahatma Gandhi, the father of the Indian independence movement, as having shaken the foundations of the British Empire.

A group of soldiers opened fire on an unarmed crowd without warning in the northern Indian city after a period of unrest, killing hundreds in cold blood.

In a message written in the visitors book, Cameron clearly described the massacre as 'deeply shameful.'

Cameron's visit and expression of regret for what happened will stop short of an apology - but will make it clear he considers the episode a stain on Britain's history that should be acknowledged.

The British report into the Amritsar massacre at the time said 379 people had been killed and 1,200 wounded. But a separate inquiry commissioned by the Indian pro-independence movement said around 1,000 people had been killed.