Victor Olisa
© Steve Brown/BBCVictor Olisa, in 2015, in post as a chief superintendent in north London.
A former senior police officer has warned that Scotland Yard appears to have lost control of London's streets and has accused the Metropolitan police leadership of a "deafening" silence as the capital's murder toll for the year moved past 50.

The day after two further murders in Hackney, east London, Victor Olisa, the Met's former head of diversity and head of policing in Tottenham, said he feared that the violence could get worse.

He warned that budget cuts and new demands on police were taking officers off the street and away from gathering intelligence. "Communities are saying we don't see the police around any more," he said. "It appears to people I have spoken to as though the police have lost control of public spaces and the streets."

Olisa said Met chiefs should have been more visible after this week's rise in violence.

"The silence from senior officers in the Met is deafening," he said. "They should say we need more information from the public; this is what we are doing; this is what the results are."

On Thursday, the Met's commander, Cressida Dick, attempted to take control of the crisis by launching a taskforce of 120 officers and telling the public: "You will see us being even more proactive out on the streets."

But Olisa said that wider cuts were making police officers' jobs harder. "You don't have as many officers available to patrol or spend time in public spaces as you did five years ago. There is less time to build conversation lines so you can get information back."

The retired officer was speaking as investigations began into two more killings in the capital, taking the suspected murder toll in London to more than 50 in three months. On Wednesday an 18-year-old man, named as Israel Ogunsola, collapsed in the street after being stabbed and a man aged 53 died after a betting shop fight.

On Thursday night, reports emerged that two more people were in hospital after a stabbing attack in east London.

Olisa's intervention was the latest in a week of fierce exchanges over the factors behind the increase in violence in London. They come against a backdrop of sustained reductions in policing numbers. By September 2017, the number of officers in England and Wales was down by 16%, against a 2009 peak, amounting to a cut of more than 22,000 officers.

Figures released in November showed a 20% annual rise in gun, knife and serious violent crime across England and Wales, even as the crime survey estimated there had been a 9% overall drop in crime. The Home Office claims that "traditional crime" nationwide has dropped by almost 40% since 2010.

Such is the demand on the Met, it is drafting in detectives from another force to investigate the latest murder. The force said on Thursday that City of London police would investigate one of two east London murders committed on Wednesday and had made an arrest.

With the murder rate in the capital such that the total for the year could reach levels last seen in 2005, when there were 181 killings, the two new murder investigations prompted Dick to make her first comments of the week on the subject.

"We will put even more effort into bearing down on violent crime," she said. "We will have a greater presence in the hotspots of violence and a focused effort, including intelligence-led stop and search and the use of specialists in covert tactics."

But critics fear that the commissioner's initiative is a short-term measure. Met chiefs accept that "supression activity" is not enough to tackle knife and gun crime. This week in the capital two teenagers were gunned down in Tottenham and Walthamstow, while others were stabbed to death or were knifed but survived.

Next week, the home secretary, Amber Rudd, is expected to announce a new government anti-violence strategy concerning interventions to deter young boys from offending.

Olisa, who retired at the rank of chief superintendent, led policing in north London after the 2011 riots. He said austerity and longstanding tensions around social inequality were again playing a part, as well as the rise of aggressive taunting on social media.

"There are frustrations building up because people feel lack of control of their destiny," he said. "There are no youth clubs, young people feel they had no access to the wealth they see that others have, there is a bigger divide between the haves and the have nots, the frustrations are building up. It could lead to a public display of anger."

He argued that the shooting of Mark Duggan in 2011, which led to the riots, had "brought up residual anger".

He said that when, in 2013, he became head of policing in Haringey, an area including Tottenham, there were six officers to every council ward in London. Now there were two.

"We can't find something to control or mitigate it," he said. "You'll never totally stop it. The level of violence seems ridiculously high. My worry is that it is a trend that will end up far worse than where we are at the moment."

In Hackney, people were stunned by the latest violence. Ogunsola, a student who had recently returned home to live with his parents, died about half an hour after being stabbed, despite the efforts of a police, paramedics and a trauma doctor from London's air ambulance.

"The policewoman's arms were literally covered in blood, you could see she had been trying to fight for this man's life," said one witness to the aftermath, who declined to give her name. "People were just coming all night, just crying and breaking down in tears."

As mourners gathered at the cordon surrounding the police forensic science tent on Thursday morning, the political argument over the violence deepened, with David Lammy, the Labour MP for Tottenham, accusing ministers of abdicating responsibility and police of failing to tackle organised crime.

Lammy told the BBC: "What we're seeing today is the worst I've ever seen it. There are parents, friends, families, schools traumatised and grieving. And there is absolutely no sign at the moment of reduction in the violence."

He said there was no single cause for the crisis, but turf wars over drugs were a big factor. "It's like Deliveroo, they're as prolific as ordering a pizza," he said. "You can get them on Snapchat, WhatsApp. That is driving the turf war and it's driving the culture of violence that's now becoming endemic."

Meanwhile two 17-year-old boys were arrested on suspicion of murder.

Ogunsola had been charged with causing actual bodily harm, dangerous driving without a licence, having no insurance and being in possession of cannabis after an incident in Stevenage in November that left a police officer with a head injury. A friend of the teenager said he had been a student at the University of Hertfordshire, in Stevenage, but had recently returned home to live with his parents.

"Israel was a nice person," said a 19-year-old, who gave her name as Petronel, as she stood by the police tape in Morning Lane. She said she had last seen him the previous day, when she had heard he was back in London. "I hugged him, thinking that I might just see him again tomorrow."