Among those arrested in connection with the last Sunday attack on 78-year-old Brar in Old Quebec Street near Oxford Street were two women.
"Officers from the Counter Terrorism Command have arrested a further eight people in connection with the investigation into the attempted murder of an Indian man (Brar) in central London on 30 September," the Metropolitan Police Service said in a statement.
It added that a further three were arrested on immigration matters unrelated to the attempted murder investigation.
The statement came as Britain's Foreign Office Minister in charge of India, Hugo Swire, called the attack on Brar "unacceptable" and "appalling", saying it was of "great concern" to the UK.
"It (the attack on Brar) is of great concern to the United Kingdom. We don't want these people here exporting their terrorist views because they represent a real threat to people in the UK apart from anything else.
"It is regarded as being as unacceptable and despicable as people in India do. These things are taken very seriously by this government. General Brar was appallingly, appallingly attacked. It would be wrong for me to comment (further) till we know who the perpetrators are," Swire said.
Meanwhile, the three people who were arrested on immigration violation charges, were nabbed from the same address where some of the suspects were held.
Giving details about today's arrests, police said two people -- a 42-year-old man and a 38-year-old woman – were arrested at a residential address in Hillingdon borough. The man was held on suspicion of assisting an offender and the woman was arrested on suspicion of conspiracy to murder.
A further three men, aged 42, 37, 30 respectively, were arrested after a short while on the street on Queensdale Road, in Kensington and Chelsea borough, on suspicion of conspiracy to murder, the statement said.
Three more people, aged 32, 31 and 20 respectively, were held at a residential address in Holland Park after a few hours. Two of them were arrested on conspiracy to murder while the third one was held on suspicion of assisting an offender.
The arrests came a day after officers took into custody three men and one woman on suspicion of conspiracy to murder in connection with the investigation into the attempted murder of Brar.
"All 15 are in custody at police stations in central London and west London," the Scotland Yard statement said.
All 15 are in custody at police stations in central London and west London.
A number of search warrants have also been executed in connection with this investigation. The searches are being carried out at a residential address in South Shields, a residential address in Birmingham and two residential addresses in London.
The statement said the attack may have caused concern among Indian and Sikh communities.
"While we are aware that there has been a great deal of speculation about possible motivation for this attack, it would not be helpful to our investigation to comment further at this stage.
"Detectives from New Scotland Yard are investigating this incident and are treating it as an attempted murder.
"They have maintained an open mind regarding the motive for this attack and the investigation will continue to go where the evidence leads," it said.
Brar, who had led 'Operation Blue Star' in 1984 to flush out pro-Khalistan militants from the Golden Temple, was on a private visit here when he was attacked by four men, suspected to be Khalistan sympathisers, while he was returning to his hotel with his wife.
He suffered a wound on his neck and cheek but his wife was not injured in the attack.
The four men who attacked Brar were described as being of Asian appearance, all with long beards, and were wearing dark clothing and long black jacket.
WE pray for his speedy recovery.
General K.S.Brar: Why do we put so much publicity of this confidential and secret General. Please stop this immediately without further reference on the subject. Without Prejudice
good follow up story, seems the police has almost crack the case
Yes - it is absolutely correct.
The news about the London Metropolitan Police grabbing some suspects in the Brar Stabbing case brings to mind the good days of Scotland Yard and the number 999 -Kranthi Sagar
I am impressed by the speed at which the law enforcement agencies in UK have got got hold of suspects. If it was in India we would have seen only statements being given by Government agencies and the politicians.