Last year 80 people were killed in knife attacks in London

Three buses on route 328 in Kensington and Chelsea, will display a poster designed by Thomas Keller, 14, of the local Cardinal Vaughan School.

The message "Knives take lives" is a part of a wider effort to improve safety in the west London borough.

Police say that people aged 12 to 20 are most likely to be both offenders and victims of knife crime in London.

Last week a teenager was convicted of murdering 15-year-old Charlotte Polius at a party in east London.

Beatriz Martins-Paes was 17 when she stabbed Charlotte to death over a dispute on the dance floor.

Knife surrender bins

The latest scheme, Operation Sabre, is backed by First, the UK's largest bus operator, Kensington and Chelsea Council and Transport for London.

Police hope to reduce knife crime through education and enforcement and a number of schemes have been tried - such as stop and search and "engagement programmes".

There are also nine "knife surrender bins" across Kensington and Chelsea, in which illegal or unwanted knives can be disposed of in a safe and secure way.

So far, 169 knives and dangerous weapons including bullets and knuckle-dusters have been left in the bins.

Tony Wilson, managing director for First's London and Berkshire companies said: "Safety is our number one priority and this campaign, which urges people to surrender their knives, will help to protect our passengers and our staff."

Police have become increasingly concerned about the number of people now arming themselves with knives - some 80 people were killed in knife attacks in London last year.