China will provide more than $11.5 billion in loans and aid to neighbouring Cambodia, Laos, Myanmar, Thailand and Vietnam, mostly for infrastructure and industrial capacity building, state media said Saturday.

Chinese Premier Li Keqiang pledged $1 billion in funding for infrastructure, $490 million aid for poverty reduction, and $10 billion in "special loans", the official Xinhua news agency said.

Li announced the loans in Bangkok at a summit of countries along the Mekong river, a day after he vowed to help construct a railway through Thailand which Xinhua said will cost $10.6 billion.

Few details were given on projects to be funded, but Xinhua said China will export production capacity in industries such as electricity, telecommunication, steel and cement.

China also promised to invest $16.4 million to dredge waterways along the Mekong River and prevent natural disasters, Xinhua cited Li as saying.

Beijing has previously come under fire from environmentalists for building dams along the upper-reaches of the Mekong in southwestern China, which have been blamed for flooding along the river.

Dams and hydro-electric power schemes were expected to be high on the agenda of the Greater Mekong Summit, despite mounting concerns over environmental and social impacts.

China has in recent months devoted diplomatic energy as well as huge sums of money to wooing Southeast Asia, where its reputation as a regional powerhouse is blighted by sea disputes and fears over its long-term intentions.

In November, Beijing pledged $20 billion in soft loans and for infrastructure projects to the 10-members of the Association of Southeast Asian nations during a summit in Myanmar.

Experts say Beijing is determined to outmanoeuvre the US, which has embarked on a security "pivot" towards Asia, as well bolster its trade routes -- and access to resources -- as China's rapid economic growth continues.