By Katherine Masters

NEW YORK (Reuters) -Republican leaders of two House committees are requesting United States Postal Service data on retailers' goods shipped from China under an exemption in U.S. trade law that excludes some packages worth $800 or less from tariffs.

The exemption, known as the de minimis rule, has earned growing scrutiny over the last few months from congressional leaders who say it unfairly benefits the China-founded retail companies Shein and its rival Temu, launched by parent PDD Holdings in the United States in September.

Temu did not immediately respond to a request for comment. Shein told Reuters it does not use USPS for its shipments from China to the U.S. and continues to make import compliance "a priority."

Republican representatives Mike Gallagher, chairman of the House Select Committee on the Chinese Communist Party, and James Comer, who heads the Committee on Oversight and Accountability, sent a letter on Wednesday to Postmaster General Louis DeJoy asking for “documents, information, and data” related to goods from China shipped into the United States.

The letter, seen by Reuters, also asked specifically for all records and data related to de minimis shipments from fiscal 2021 and 2022.

"Chinese companies can take advantage of the de minimis rule and ship products via commercial shipping companies, as well as the USPS, directly to U.S. consumers without paying duties and fees or subjecting their products to investigation by authorities,” the request reads.

Gallagher’s select committee released a separate report earlier this week estimating that Shein and Temu accounted for more than 30% of all de minimis shipments sent to the United States.

There are currently two bipartisan bills in Congress that take aim at the e-commerce companies by proposing a ban on e-commerce shipments from China and other non-market economies.

(Reporting by Katherine Masters in New YorkEditing by Mark Porter and Matthew Lewis)