China on Wednesday expressed “strong indignation and firm opposition” to the U.S. House of Representatives’ passage of a bill in support of Hong Kong protesters.

The Hong Kong Human Rights and Democracy Act requires sanctions against Chinese officials “responsible for undermining fundamental freedoms” in the city.

It also provides an annual review of whether Hong Kong is sufficiently autonomous from Beijing to maintain a special trading status with the U.S.

The Hong Kong government also expressed “regret” over the bill passing in the U.S. House.

“Foreign legislatures should not interfere in any form in the internal affairs” of Hong Kong, the statement said.

Hong Kong is a semi-autonomous Chinese territory, which has for months been rocked by massive pro-democracy protests.

Tens of thousands marched in the city on Monday in support of the bill, which still needs to pass through the U.S. Senate.

The bill has put further strain on China-U.S. relations, as the two countries are negotiating an end to their year-long trade war.