China has pledged $20bn in credit to Africa over the next three years and called for more China-Africa co-ordination in international affairs to defend against the "bullying" of richer powers.
Hu Jintao, China's president, made the announcement on Thursday at a summit in Beijing with leaders from 50 African nations.
The credit line is double the amount offered in 2009 at the last forum held in Egypt.
"We want to continue to enhance our traditional friendship... rule out external interference and enhance mutual understanding and trust," the Chinese president said.
Hu said the loans would support infrastructure, agriculture and the development of small businesses.
The Chinese leader also called for better co-operation with African countries on international affairs, and promised more Chinese help for African countries in building agricultural technology centres, training medical and other personnel, and digging wells to expand access to clean water.
"We should oppose the practices of the big bullying the small the strong domineering over the weak and the rich oppressing the poor," Hu said.
China will encourage investment and assistance in infrastructure that facilitates trade within Africa, he said.
China has emerged as Africa's main trading partner and a major source of investment for infrastructure, pouring billions of dollars into roads and developing the energy sector across the continent.
Trade between the two sides hit a record $166bn last year, a three-fold increase since 2006.
In his remarks, Hu stressed China's status as a still-developing nation and noted Africa is the region with the world's largest number of developing countries. He said both should jointly work to defend their interests in global forums such as the United Nations.
Some observers see Chinese investment in Africa as an unequal partnership between an emerging economic giant and the world's poorest continent and accuse Beijing of offering no-strings-attached investment for repressive regimes.
The Asian giant has been criticised for ignoring environmental issues and labour disputes in Africa.
The Chinese president pledged that his country would pay more attention to environmental protection and cultural issues in its dealings with the continent.