Sinn Fein president Gerry Adams and the daughter of Che Guevara will be among the speakers at an event to be held in Southwark Cathedral on Thursday evening.
Ken Livingstone, Mayor of London, will also speak at the free event he is hosting which will give Londoners an opportunity to welcome the European Social Forum to the capital.
Other speakers will include Dr Aleida Guevara, daughter of Ernesto (Che) Guevera; Dr Susan George, who writes on third world debt issues; Frances O'Grady, TUC Deputy General Secretary; Sinn Fein president Gerry Adams; Meena Menon, who writes on the environment, health and women's issues; Thenjiwe Mtinstso, South African Ambassador to Cuba; and Cllr Charles Adje, leader of Haringey Council.
The welcome event takes place on the eve of the European Social Forum, which is expected to attract up to 20,000 people from across the world. The event is open to all, including people not registered for the forum.
The forum will take place over three days in Alexandra Palace and Bloomsbury, with debates, workshops and a linked cultural programme. It will cover six main themes: war and peace; democracy and fundamental rights; social justice and solidarity; corporate globalisation and global justice; racism, discrimination and the far right; and the environmental crisis and a sustainable planet.
Recognising the controversial nature of some of the speakers, a statement from the Dean of Southwark Colin Slee explains the cathedral's reasons for agreeing to host the event: "Gospel values and the search for justice and reconciliation inevitably involves listening and speaking to people of strongly opposed perspectives in many matters. A lack of understanding or respect for the humanity of one's opponent is frequently at the heart of much of the discord we face in the world today; that lack is only remedied by proper exchanges and openness towards one another.
"It is for these reasons that we welcome the ESF to this Cathedral in the hope that, whatever the past history of the participants and the speakers, it can be an occasion when we offer hospitality to everyone who searches for answers to the discord, injustice and violence we all aim to see remedied."
• The event starts at 7pm on Thursday 14 October at Southwark Cathedral, London Bridge.