WASHINGTON, Feb 26 (Reuters) - Chinese passenger airlines will be allowed to boost their weekly round-trip U.S. flights to 50 starting on March 31, up from the current 35, the U.S. Transportation Department said on Monday, returning the market to about one-third of pre-pandemic levels.

The approval "is a significant step forward in further normalization of the U.S.-China market in anticipation of the Summer 2024 traffic season," the USDOT said.

More than 150 weekly round-trip passenger flights were allowed by each side before restrictions were imposed in early 2020 due to the COVID-19 pandemic, but until August 2023, Chinese and U.S. carriers could each fly only 12 a week between the two countries.

The number rose on Sept. 1 to 18 weekly round-trips and then to 24 per week starting Oct. 29. The USDOT approved 35 for Chinese carriers in November.

A group representing major U.S. airlines did not immediately comment. Reuters reported last June that newly approved Chinese flights to the United States were not overflying Russia, which would have given them a shorter flight time and fuel advantage over U.S. rivals blocked from Russian airspace.

The USDOT said it was engaged in a productive dialogue with China's aviation regulator towards the "implementation of a roadmap to provide for a gradual, broader reopening of the U.S.-China air services market and a phased and predictable return to the capacity entitlements" specified under a U.S.-China agreement.

On a trip to China last year, U.S. Commerce Secretary Gina Raimondo said she wanted to boost travel and tourism between the two countries.

If China returned to 2019 U.S. tourism levels, it would add $30 billion to the U.S. economy and 50,000 U.S. jobs, Raimondo said in August.

China last month simplified visa applications for tourists from the United States, cutting the number of documents required.

The move was the latest by China to revive tourism and boost the world's second-largest economy following a slump during the pandemic.

The number of inbound tourists to the country plummeted during that period due to the country's strict COVID control policies. (Reporting by David Shepardson; Editing by Leslie Adler and Jamie Freed)