One billion people worldwide lack access to safe drinking water and countries must try harder to reach their goals on sanitation, UN Secretary-General Ban Ki-Moon said on Monday.   

'There has been progress towards achieving the water and sanitation Millennium Development Goals, but not enough,' Ban said in a speech at the water-themed International Exposition in Zaragoza in northern Spain.

The goals, signed by UN member countries in 2000, aim to halve the number of people without access to safe drinking water by 2015. But the fall so far has only been 10 percent, due to population growth and persistent poverty, the UN chief said.

About 1.2 billion people have gained access to improved water sources since 1990, while estimates indicate the world population will rise to 9 billion from 6.5 billion by 2050.

'The international community, national governments and the private and non profit sectors still have much work to do between now and 2015,' Ban said.

Climate change was making it more difficult to meet the water targets, he said.

'As the earth warms, people who rely on snowfall and glaciers in high mountain ranges to replenish their water supplies have serious cause for concern'.

On Sunday, Ban said world leaders should not wait until a planned Copenhagen summit in 2009 to put together a climate change pact to succeed the Kyoto Protocol.

Other challenges facing efforts to improve access to clean water include financially unsustainable water utilities in the developing world, the slow pace of policy and institutional reform and the rapid growth of urban slums, he said.

Ban has previously said competition for water is a root cause of the five-year conflict in Darfur thought to have killed more than 200,000 people and displaced over 2.5 million.-Reuters