NEW YORK/LONDON (Reuters) - GlaxoSmithKline Plc hopes to seek approval by 2012 for its experimental malaria vaccine and said on Wednesday it would seek only a small profit and ensure it is widely available in hard-hit countries.

Chief Executive Andrew Witty also said the company would give away access to a stock of 13,500 potential malaria treatments for others to test and develop further if they show promise against the disease.

Glaxo will likely derive a "small 5 percent return" on the vaccine, Witty said, enough to help encourage other drugmakers to continue their own research against diseases that remain big killers in least developed countries.

"(Its) sales in dollars will be a very small number," he told reporters ahead of a planned speech on Wednesday to the Council on Foreign Relations in New York.

"We must ... ensure that we do not do anything which would discourage other companies from entering into this field," he said, adding that Glaxo's return would be reinvested into research on medicines for diseases in poor countries.

"If we set a precedent of not-for-profit (pricing), we could discourage others from doing research into malaria or other neglected tropical diseases."

The Mosquirix vaccine is expected to complete late-stage trials in 2011 involving 16,000 people. If proven effective, and approved by regulators, it would be the first to protect against infection with mosquito-borne parasites that cause malaria.

"If it lives up to its promise, I think it's incredible," Witty said. He said it could be a major weapon in the battle against the disease, which kills more than 1 million people a year worldwide, most of them children in Africa and Asia.