Four leading housing organisations launched a worldwide campaign to halve the number of people living in slums.
Over the next few years, Homeless International, Chartered Institute of Housing, hact and the National Housing Federation will be campaigning to raise awareness of this issue and to bring a greater understanding of the challenges faced by slum-dwellers.
At present, one third of the world's urban population - one billion people - live in slums.
Speaking at the Chartered Institute of Housing's Annual Conference and Exhibition in Harrogate, Larry English, Chief Executive of Homeless International, said:
"There are 100,000 people moving into slums everyday. If trends continue, the world slum population is forecast to reach 1.4 billion by 2020.
"We have a huge challenge ahead of us but we can no longer ignore this issue and we hope the collective voices of our organisations will move governments across the world to take action."
The campaign also has a longer term ambition to gain agreement for a new target that no one should be a slum dweller.
The London Mayor's Director of Housing, Richard Blakeway, spoke at a conference organised by Thames Reach for the homeless and formerly homeless people who use the Charity's services.
He was among guests on a panel invited to answer questions on homelessness issues posed by Thames Reach service users.
Among the topics covered were the problems faced by Central and Eastern European rough sleepers in the UK, and the ways in which homeless people could help shape future homelessness policy.
A series of workshops were also undertaken, allowing participants to look at a range of issues - including pathways back into work and health awareness.
Jeremy Swain, Thames Reach Chief Executive, said:
"This was a particularly stimulating conference which highlighted the keen interest Thames Reach's service users have in shaping the direction of travel of the organisation and the great value of hearing from people who have directly experienced homelessness."
