British police have arrested three people in an investigation into the attempted murder of an Indian army general stabbed last week near London's busy Oxford Street.

Lieutenant-General Kuldip Singh Brar, who helped lead a deadly 1984 raid in India on Sikhism's holiest shrine, was set upon by four men and slashed in the neck as he walked with his wife shopping on September 30.

Brar, 78, was treated in a London hospital and released.

Scotland Yard said on Thursday it had arrested a 33-year-old man and a 40-year-old woman on suspicion of conspiracy to murder. It said another man in his 30s also was arrested.

The four men have been described as being of Asian appearance, all with long beards, and were wearing dark clothing and long black jackets.

One has been described as younger and slimmer than the other three.

Speaking to Indian media, Brar said that he "kicked and boxed and warded off the attack", and that he had sustained a slash to his neck.

He said he was attacked due to his role in the storming of the Sikh Golden Temple in Amritsar, an operation in which more than 1,000 people were killed.

Twenty-eight years ago, on then-prime minister Indira Gandhi’s instructions, Brar led Operation Blue Star, to flush out fighters holed up in the Golden Temple demanding an independent Sikh homeland.

Four months after Operation Blue Star, Gandhi was assassinated by two Sikh bodyguards in retaliation. This triggered national anti-Sikh riots in which thousands of people were killed, mostly in the streets of the capital, New Delhi.

SM Krishna, India's foreign minister, who is in the US at present, said the Indian government would take up the investigation into the attack on Brar with British authorities.