HONG KONG (Reuters) - China's state planner said on Tuesday it held a meeting with private domestic companies, including Trina Solar, ride-hailing company Didi and Goertek, to hear suggestions about how to deal with additional U.S. tariffs.

The meeting, which took place in Beijing on April 8, was attended by Zheng Shanjie, chairman of China's National Development and Reform Commission (NDRC), the state planner said in a statement.

It comes as China vowed not to bow to "blackmail" from the United States after Trump threatened to ratchet up tariffs on U.S. imports from the world's No. 2 economy to more than 100% on Wednesday.

This was in response to Beijing's decision to match 'reciprocal' duties Trump initially unveiled last week.

During the meeting the companies gave opinions and suggestions on stabilising employment in China and how to respond to external risks and challenges, the NDRC said.

"The domestic development environment is stable and companies are confident to overcome difficulties," it said.

Zheng said in "the face of external risks and challenges such as the imposition of tariffs by the United States, we must unify our thoughts and actions with the decision-making."

The NDRC will actively help private companies solve difficulties and promote the healthy and high-quality development of China's private sector economy, it said.

(Reporting by Farah Master and the Beijing newsroom; Editing by Tom Hogue and Muralikumar Anantharaman)