Jeremy Corbyn has urged activists to engage in "civilised debate" after ugly scenes at demonstrations outside the Conservative Party conference.

The Labour leader told supporters that people involved in politics should not engage in "personal abuse" as he addressed a protest rally attended by thousands in Manchester city centre.

His speech came after tens of thousands of activists marched through the city centre to protest about Government policies on the conference's opening day.

The march, involving about 60,000 people, was largely peaceful but some activists spat at journalists entering the Manchester Central venue and police made four arrests.

Speaking to a cheering crowd at the public event organised by the Communication Workers Union, Mr Corbyn said: "If we go into politics, we go into our union work, we go into our lives on the basis that what we say we hope is of value, what the other person says we hope is of value, and we engage in an intelligent, civilised debate, not responding to personal abuse and not making personal abuse."

The Islington North MP gave speeches inside and outside Manchester Cathedral following the event after the rally spilled on to the surrounding grounds because it was so oversubscribed. Organisers estimated that around 7,000 people turned up for the two-hour event.

Leaders of the main parties traditionally stay away from rivals' conferences but Mr Corbyn broke the convention to give his support to the CWU campaign to protect postal services and employment standards in the postal industry.

He said: "Because we have challenged the idea that the only show in town is austerity, the only show in town is hitting the living standards of the poorest working class communities, the only show in town is cutting more public services, because we have challenged that, because we have this huge mandate in challenging that, suddenly people are talking, people are talking to each other, people are more excited about the world that we live in."