A CRH (China Railway High-Speed) train is seen at a maintenance station for an overall system examination in Urumqi city, northwest Chinas Xinjiang Uygur autonomous region, June 3, 2014. [Photo/IC]

China's National Railway Administration has officially unveiled the country's first design specification standards for high-speed rail links.

The NRA laid down standards for nearly 20 fields involved in the design and construction of lines for bullet trains running at speeds of 250-350 kilometers per hour.

Railway construction firms were also asked to reduce pollution and to work in a more "greener" way.

Driven by its "go abroad" ambitions, Chinese railway firms are seeking more opportunities in other countries.

With this in mind, the NRA's specifications include domestic experience as well as advice from foreign experts.

China has seen rapid development in the construction of high-speed railways and it is now eyeing selling equipment and technology it has developed to foreign markets.