(Adds no immediate comments from companies in paragraph 3, details from letters in paragraphs 4-6, background in paragraph 7-8, byline)

WASHINGTON, Nov 16 (Reuters) - A bipartisan group of U.S. lawmakers raised alarm about Chinese companies collecting and handling sensitive data while testing autonomous vehicles in the United States, according to letters seen by Reuters on Thursday.

The lawmakers, including House of Representatives Energy and Commerce Committee Chair Cathy McMorris Rodgers and China select committee Chair Mike Gallagher, asked 10 Chinese-related companies to answer questions by Nov. 29 on data collection practices from ongoing autonomous vehicle testing in California and elsewhere.

The companies - including Baidu, Nio, WeRide, Didi Chuxing, Xpeng, Inceptio, Pony.ai, AutoX, Deeproute.ai and Qcraft - did not respond to requests for comment or could not immediately be reached.

The previously unreported letters, also signed by Democrats Frank Pallone and Raja Krishnamoorti and 10 other lawmakers, said the companies "collect sensitive information about our citizens and their daily routines, the nation's infrastructure, and connected technologies."

"There needs to be greater transparency around what information you collect while testing on American roads, and whether you are financially tied to the Chinese Communist Party," according to the previously unreported letters.

The lawmakers asked what data is collected in the United States, whether it is stored in China, and if it is shared with the Chinese government or others. They also asked if the vehicles collect data on U.S. infrastructure during testing.

The letters said in the 12 months ended November 2022 that Chinese AV companies test drove more than 450,000 miles in California.

In July, Transportation Secretary Pete Buttigieg said his agency had national security concerns about Chinese autonomous vehicle companies in the United States.

"Whether we are talking about hardware or software, in the same way there are concerns around telecom or TikTok, there are concerns around transportation technologies," Buttigieg told Reuters.

(Reporting by David Shepardson; editing by Jonathan Oatis and Richard Chang)