Gordon Brown has promised to tackle bullying in schools.
Ben Vodden hanged himself after he was bullied, an inquest heard
He confirmed that, as prime minister, he and his government will continue to back teachers who physically restrain aggressive pupils.
His pledge coincided with a call by the Beatbullying charity for people to take a stand and refuse to tolerate it.
Beatbullying supporter Dame Kelly Holmes said: "Millions of children get bullied every year, and it's terrible - lives are actually ruined."
The charity asked school children and adults across the UK to take part in its Big Stand event at 1000 BST in solidarity with people who are bullied.
New powers for head teachers to deal with badly-behaved pupils including those who target other children on their way to and from school came into effect last month.
Labour deputy leadership contender Hazel Blears said she wanted to see more community police units brought into schools, "so bullies know they cannot get away with it".
The general secretary of the National Union of Teachers, Steve Sinnott, said Mr Brown was absolutely right to highlight the recent new powers.
He said the Department for Education and Skills had given them a low profile, which needed urgent action.
"We need a high profile publicity campaign for parents, teachers and young people emphasising the potential in the legislation for supporting schools in tackling the behaviour of the few who can make life a misery for the many."
Mr Brown, Ms Blears and Dame Kelly took part in the Big Stand by joining children at St Johns Church of England Primary School, in Croydon, south London.
Dame Kelly told BBC News the event was "an act of defiance" against bullying.
She said: "Millions of children get bullied every year, and it's terrible - lives are actually ruined and so it has to be a big stand.
"Over a million people took place in this campaign last year and we're hoping that more will."
A recent survey suggested more than 40% of secondary school children have been the victim of violence.
Last month an inquest heard that 11-year-old Ben Vodden, from Southwater, near Horsham, West Sussex, hanged himself from his bunk bed after being subjected to months of bullying on the school bus.