Relatives of a man who died after jumping from a bridge having been Tasered said the “excessive and unnecessary force” of officers means they are “solely responsible” for his death.

The family of Oladeji Adeyemi Omishore, 41, who died after a confrontation with two officers on Chelsea Bridge on June 4, have said they will campaign for “change” in the Metropolitan Police to ensure his death was not “in vain”.

Details released by the Metropolitan Police in the aftermath of the incident said that officers had been called to reports that a man was “armed with a screwdriver”.

In June, watchdog the Independent Office for Police Conduct (IOPC), confirmed that in fact Mr Omishore, who was known by his family as Deji, had been carrying a plastic and metal firelighter, which relatives said he used to light cigarettes.

His father Alfred told The Guardian: “The Metropolitan Police are solely responsible for his untimely death, in the sense they used excessive and unnecessary force on him.

“At a time it was obvious he going through a crisis. Using a Taser on vulnerable people like Deji is very wrong.

“We have taken this tough decision to speak out to the public because we know that Deji met his untimely death because of the police actions on him.”

The former Home Office civil servant went on: “It was too painful, he was on the floor, and they kept on using the Taser on him repeatedly. He was in pain, was holding his chest. They had the opportunity to restrain him, deescalate.

“The impact of the pain, the unbearable pain, must have led him to jump to the river.”

The family said Mr Omishore lived close to the spot where he was Tasered.

His sister Aisha said he did not leave home intending to end up in the river, adding that he may have jumped the barrier to escape the Taser.

His other sister Remi went on: “What we witnessed was a reflection of the systemic issue that are plaguing the Met in terms of their practices, discriminating against especially black men, and black men with vulnerable, underlying mental health or health condition.

“As a family, we were outraged, absolutely outraged by what we witnessed, and it’s unacceptable.

“It is clear from the video footage that we saw, that he is clearly in distress, he is clearly frightened, and he needed help.”

She also told Channel 4 News: “I think this speaks to the systemic issues that we are seeing with the Met Police in terms of them trying to control the narrative to portray my brother as this menacing person.”

His brother Kenny said: “Our responsibility is to ensure that our brother’s death wasn’t in vain, to advocate for change in the Met Police and their conduct.

“They failed to show compassion in a moment where our brother was essentially crying out for help.”

An IOPC spokesperson said: “Our thoughts and sympathies remain with the family and friends of Oladeji Omishore.

“Our investigation into the circumstances surrounding his death is progressing well and our investigators are continuing to gather and analyse key evidence.

“At this early stage we have no indication that any of the officers involved may have breached police professional standards or committed a criminal offence, although we keep conduct matters constantly under review.

“We will work to complete the investigation as quickly as possible and we are committed to carrying out a thorough and robust examination of all the evidence.

“We continue to liaise with Mr Omishore’s family to update them on our progress.”