Pfizer is transferring many of its drug trials from Japan to South Korea in a bid to avoid the country's higher costs and regulatory obstacles, it has emerged.

In comments reported by Bloomberg, Pfizer's head of research at its Tokyo unit Akihisa Harada highlighted the study transfer as many Japanese hospitals found it more difficult to test patients.

He added that studies in Japan can cost up to twice as much as in the US and Europe, which drove up costs and delayed drugmakers' profits.

Last year, Pfizer confirmed that its research in centre in Japan was to close and later announced plans to spend $300 million (150 million pounds) on research and development in South Korea.

Bae Ki Dal, a pharmaceutical analyst with Good Morning Shinhan Securities, commented: "It's somewhat natural to pick South Korea as an alternative research & development centre in Asia because it costs less, while Korean doctors have relatively good medical expertise."

He also illustrated that Japanese approval was slower than in the US and Europe with more regulatory obstacles in place.

However, the Pharmaceuticals and Medical Devices Agency in Tokyo has announced that it is take on over 200 more drug reviewers to reduce the approval time by up to 30 months.

Also this week, Pfizer announced that it has voluntarily withdrawn an advertising feature for Lipitor featuring Dr Robert Jarvik.