Mining group Rio Tinto says Chinese building boom will continue to drive up materials demand

China will build up to 50,000 skyscrapers in the next 20 years, according to one of the world's largest mining companies.

Rio Tinto, the Mexican mining giant, has based its forecast of a continuing rise in demand for steel and materials partly on a predicted building boom in China, with the equivalent of 10 New Yorks to be built before 2025.

The group cited research by analyst McKinsey which concluded that China would have 221 cities with more than 1m inhabitants by 2025, with between 20,000 and 50,000 new skyscrapers. There are at present only 35 cities of that size in the whole of Europe.

Rio Tinto made the prediction as it reported half-year profits of $5.5bn (£3bn), up 55% from the same period last year. The Chinese market provided $4.9bn (£2.7bn) of Rio Tinto's $30bn (£16bn) revenue.

Prices in the international materials markets continue to rise. In the first half of 2008, Rio Tinto raised its iron ore price by an average of 86% compared with the same period last year. Copper was up 20%, gold higher by 38% and aluminium by 2%.

Tom Albanese, chief executive of Rio Tinto, said: “There is no question that we are living in an era of unprecedented demand for minerals and metals.”