European and U.S. carmakers are waiting for more details about the possibility of expanded access to China's market after President Donald Trump tweeted that China had agreed to "reduce and remove" tariffs on imports of U.S.-made cars.

"China has agreed to reduce and remove tariffs on cars coming into China from the U.S. Currently the tariff is 40%," Trump wrote amid a flurry of tweets on Dec. 2, in which he also spoke of an "extraordinary" meeting with China's President Xi Jinping at the G-20 summit in Buenos Aires, Argentina, on Dec. 1.

The meeting took place as a far-reaching trade war between the partners enters its sixth month, raising costs for consumers in both countries and prompting some to cut or defer consumption of affected imports.

A report from Shanghai in The Wall Street Journal said Chinese government officials neither confirmed nor denied Trump's assertion and had skirted around questions on it.

Automakers that produce vehicles in the U.S. and export to China became subject to a 40% tariff beginning in July, up from 15% previously. Some manufacturers have squeezed profit margins to maintain market share or had to watch sales plummet as the tariffs add thousands of dollars to the sticker price of new vehicles.

Although the stock market was up following Trump's tweet and the prospect that U.S.-made cars would become more competitive, representatives at major German automakers, in addition to Volvo, all of which build some models in the U.S. for export to China, said they were waiting for further confirmation.

"We are aware of President Trump's tweet and we are continuing to monitor the situation. It hasn't resulted in any decisions from our side," Christina Zander, a spokeswoman at Volvo Cars, told S&P Global Market Intelligence.

Spokespersons at BMW and Daimler said it was too early to respond with no additional information beyond Trump's tweet.

A spokesperson at Volkswagen AG noted that none of the cars it sells in China are produced in the United States and that it has been unaffected.

Bayerische Motoren Werke AG Frankfurt-listed stock ended 4.9% higher at €75.89 while Daimler AG the maker of Mercedes and Smart cars rose 3.75%. Volkswagen appeared to benefit from the sector's buoyancy and potential warming in trade relations with its stock climbing 2.9% to €153.18.

In the U.S., stock in both Tesla and Ford had risen 2.9% by early afternoon trade in New York to $360.62 and $9.68, respectively.

Ford Motor Co. told S&P Global Market Intelligence in a statement that the automaker looked forward to learning more.

"We are encouraged by the trade discussions over the weekend and reiterate our position that it is essential that governments work together to advance balanced and fair trade," the company said.

Trump's tweet came after he announced he had agreed to temporarily delay a scheduled rise in tariffs on $200 billion of Chinese imports to 25% on Jan. 1, 2019. That tranche of tariffs, currently set at 10%, is part of a steadily growing list of tit-for-tat tariffs between the U.S. and China. In return, the White House said in a statement that China had agreed to ramp up its purchases of U.S. agricultural produce, energy and industrial goods to narrow the deficit with its biggest trading partner.