Ilford South MP Sam Tarry quizzed Boris Johnson on whether he would meet the mother of a teenager who was fatally stabbed - but the PM was non-committal.
Mr Tarry raised the case of 18-year-old Kamran Khalid in the House of Commons during Prime Minister's Questions on February 23.
Kamran died after the fatal stabbing in Loxford on October 28.
Mr Tarry told the Commons: "I hope that the prime minister would agree with me that far more needs to be done to stamp out the scourge of knife crime, including addressing the underlying causes.
"Will he agree to meet me and Kamran’s mother Samina, who has said that losing her 18-year-old son has “left a void in her heart forever”, to discuss what more can be done to make our streets safer and ensure that other families do not ever have to suffer this heartbreaking loss?"
Along with other bereaved mothers, Samina attended a candlelit vigil outside New Scotland Yard in December calling for an end to knife crime.
At that time, she said: “I’m still mourning, grieving and in disbelief.
“Knife crime affects the whole community. There are no winners with knives.”
In response to Mr Tarry, the prime minister said: "I totally share the honourable gentleman’s feelings about his constituents and the tragic loss in the family concerned.
"We must crack down more on knife crime. That is one of the reasons we are putting more police out on the streets.
"It is also why we are rounding up the county lines drugs gangs, who play a big part in this, sadly. We have done 2,000 so far and there is more to do.
"That is why we are recruiting many more police and giving them the powers they need to come down hard on those gangs."
Mr Tarry has since written to the PM reiterating his request for a meeting with Mr Johnson and Samina.
Ashraf Binabdulaziz, 24, and Abubakar Binabdulaziz, 18, both of Eton Road, Loxford, as well as a 15-year-old boy, who cannot be named for legal reasons, have been charged with murdering Kamran.
They have all pleaded not guilty and will appear at Basildon Crown Court for a pre-trial review on April 29.
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