The United States voiced strong opposition on Wednesday to China's plans to curb exports next month on gallium and germanium, metals crucial for producing semiconductors, adding further tension to a bilateral relationship already fraught with numerous economic and security issues.

"We firmly oppose the export controls," a Commerce Department spokesperson said, referring to the measures announced by China earlier this week. "The United States will engage with our allies and partners to address this and to build resilience in critical supply chains."

The new development came as the United States and China seek to stabilize their complicated relationship by increasing the frequency of high-level talks.

The U.S. statement was made on the same day that Treasury Secretary Janet Yellen left for a four-day visit to Beijing to meet with senior Chinese officials.

China's Commerce Ministry abruptly said Monday that the controls on the two metals, which are vital for the production of many other electronics goods, will take effect on Aug. 1. It said the decision has been made to protect "national security."

Chinese officials have expressed their strong opposition to efforts led by the United States to hobble the Asian power's ability to develop advanced semiconductors.

The Chinese announcement, which has sent shockwaves to manufacturers around the world, is seen by officials as a retaliation to the United States and its allies, such as Japan.

Japan has followed the United States in tightening its export controls, in a bid to limit China's access to cutting-edge chip technology.

Japan's industry minister said Tuesday that the country will assess the potential effects of the Chinese restrictions and will "respond appropriately in line with international rules laid out by institutions including the World Trade Organization if the measures are unjust."

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China to curb exports of raw materials used for chip production