HONG KONG (Reuters) - Hong Kong will file a complaint on recent U.S. tariffs imposed on the city to the World Trade Organization, claiming the U.S. has completely ignored the city's status as a separate customs territory, chief secretary Eric Chan said on Tuesday.

"This is absolutely inconsistent with the WTO rules. Of course, they have totally disregarded Hong Kong is a separate customs territory," Chan, the China-ruled city's number two official, told reporters.

"We will file a complaint to the WTO regarding this unreasonable arrangement," he said without giving specifics.

Chan was responding to a U.S. decision to impose 10% tariffs on goods from the Asian financial hub as U.S. President Donald Trump targets Chinese imports.

The U.S. Postal Service last week suspended all inbound mail and packages from China and Hong Kong, then reversed that decision soon afterwards.

The move to stop accepting parcels from China and Hong Kong had caused chaos and confusion among retailers and express shipping firms over how to deal with the U.S. tariffs.

"All I can say is the policies are mercurial," said Chan.

Trump's move also included closing the "de minimis" duty exemption for packages valued at under $800, with the stated aim of stopping the flow of fentanyl and precursor chemicals into the United States.

Hong Kong has long been known as a free and open trading hub, but China's imposition on Hong Kong of a sweeping national security law in 2020 drew criticism from the U.S. and led it to end the former British colony's special status under U.S. law, escalating tensions between China and the U.S.

The U.S. subsequently stipulated that goods made in Hong Kong for export to the U.S. needed to be labelled as made in China, ending one of Hong Kong's longstanding competitive advantages as a trading hub.