WASHINGTON (REUTERS) - Tesla Inc Chief Executive Elon Musk took to Twitter on Thursday (March 8) to call on US President Donald Trump to challenge Chinese auto trade rules.

In a series of tweets aimed at the president, Musk said he was "against import duties in general, but the current rules make things very difficult. It's like competing in an Olympic race wearing lead shoes."

Tesla "raised this with the prior administration and nothing happened. Just want a fair outcome, ideally where tariffs/rules are equally moderate. Nothing more. Hope this does not seem unreasonable," Musk wrote.

Trump quoted one of Musk's tweets in his announcement on new tariffs and said American automakers have not been treated fairly by trade rules around the world.

Politicians "have known it for years and never did anything about it. It's got to change," Trump said, saying he plans to impose a "reciprocal tax" on other countries. "We're changing things," Trump added. "We just want fairness."

Tesla has sought to build a factory in China, and last November (2017), Musk said he hoped the plant would be operating within three years. However, Tesla and Chinese authorities have yet to announce an agreement.

In a tweet, Musk said no "US auto company is allowed to own even 50% of their own factory in China, but there are five 100% China-owned EV auto companies in the US."

Late Thursday, Musk shifted his tone. "To be clear, I think a fair outcome for all is quite likely. China has already shown a willingness to open their markets and I believe they will do the right thing," he said on Twitter.

Tesla shares closed down 1 per cent on Thursday and were off nearly another per cent in after-market trading.

China, the world's largest auto market, has required foreign automakers to build factories in 50-50 joint ventures with domestic Chinese automakers and not allowed them to establish wholly owned factories.

Trump told Reuters in an interview in January that "we have helped to build China because they have taken out so much money in terms of trade deficits with this country."

He added that "when China or another country charges us 50 per cent tariffs - more than that in some cases - and we charge them nothing, that's not fair. That's not fair."

China levies a 25 per cent duty on sales of imported vehicles. Those are problems for Tesla, which wants to expand its presence in China's growing electric vehicle market without compromising its independence or intellectual property.

China said last year it would gradually reduce its auto import tariffs.

Musk noted that a US car "going to China pays 25% import duty, but a Chinese car coming to the US only pays 2.5%, a tenfold difference."

He asked Trump: "Do you think the US & China should have equal & fair rules for cars? Meaning, same import duties, ownership constraints & other factors."

Trump said the United States plans to charge countries a "mirror tax" for what American products face.

Musk has met with Trump on several occasions since his election in November 2016. In June 2017, Musk withdrew from a pair of White House advisory councils after Trump said he would withdraw from the Paris climate accord.