MUNICH, Sept 6 (Reuters) - China's electric vehicle industry leaders from policy adviser and 'father of EVs' Wan Gang to the heads of carmakers BYD and Nio and battery maker CATL called for stronger global cooperation and standardization in policy to ease the technological transition.

Wan, a key figure in leading China's development of electric vehicles, said efficient batteries, better EV architectures and intelligent driving systems were the three key technologies required to boost EV uptake.

Differences in policy, industrial foundations and the level of technological development were leading to a growing disparity in EV growth across global regions, said Robin Zeng, chairman of the world's largest battery maker CATL.

The executives were speaking at the World New Energy Vehicle Congress (WNEVC) in Munich, happening for the first time outside China in a symbol of Chinese EV makers' ambitions for expansion.

"We want to invite partners from Germany to join BYD to promote green transport," BYD chairman Wang Chuanfu said.

"Our German colleagues are using China as a basis for research and development, and they were correct to position their operations this way. That puts pressure on us too," said William Li, CEO of premium EV maker Nio.

Chinese EV executives from companies including start-up Xpeng, Leapmotor and SAIC have called in recent days for more partnerships with German automakers, expressing admiration for the innovations on display at Munich's IAA conference.

Chinese companies are seeking the higher margins overseas markets can offer, hoping to leverage German automakers' scale and branding to boost their own sales and survive China's increasingly crowded EV market.

Wan, the chairman of WNEVC, advocated for developing hydrogen fuel cell vehicles and plug-in hybrids alongside all-electric battery vehicles, a message echoed by BMW's CEO Oliver Zipse who called on China to expand its hydrogen charging network.

In a closed-door plenary before the congress, executives across German and Chinese industry discussed topics such as homogenizing standards for tracking carbon emissions across the supply chain.

"We need to promote the whole supply chain of low-carbon development," Wan said.

Wan, the former science minister, is often referred to as the 'father of EVs' in China's state media for his role in urging China's government to invest heavily in low-emission vehicles.

After 15 years in Germany studying and working at Volkswagen's Audi, he returned to China in 2000 to lead a government-led initiative to develop the EV market.

The experience in Germany "helped me to understand how companies achieved technology innovations and application," Wan said, addressing Germany's top auto executives and industry officials at the opening of the WNEVC.

(Reporting by Zhang Yan, Victoria Waldersee; Editing by Friederike Heine and Elaine Hardcastle)