Addressing one of Britain's largest anti-racist demonstrations, he called for the inclusion of the new offence in next week's Criminal Justice Bill.
'We need a new offensive against racial harassment,' he told demonstrators at London Fields, east London. 'Racism must be seen as an aggravating feature of violent attacks.'
Police estimate that 30,000 people took part in the TUC- organised march and rally from Spitalfields Market and through the East End, which has seen a rise in racist attacks since the election of a BNP councillor. Organisers claimed there were up to 50,000 demonstrators on the peaceful march.
About 1,000 police officers lined the route and surrounded two pubs believed to be used by neo-Nazis.
Messages of support for the rally came from Nelson Mandela and Paul McCartney.
Controversy surrounded yesterday's event before it started. An offer by the Liberal Democrat leader, Paddy Ashdown, to speak at the rally was rejected because of his party's involvement in the production of allegedly racist leaflets in Tower Hamlets last year.
Mr Ashdown commented: 'It seems to make a mockery of the slogan 'Unite Against Racism'.
'To play race for politics is a profoundly dangerous move and I am truly sorry that the TUC seems to be prepared to make us a vehicle for this.'
But the local MP, Peter Shore, said he believed the Liberal Democrats had failed to deal with the problem in Tower Hamlets.
'I am sure there will be a large number of Liberal Democrats marching today but anti-racist groups in the area do not trust the Liberal Democrats any more. They have refused to allow open spaces in Tower Hamlets to be used for the rally, which is why we have moved to neighbouring Hackney.'Reuse content