The United States again extended tariff exemptions for hundreds of Chinese products once hit by punitive duties, US trade officials announced Tuesday.

The exemptions, which had previously been extended until December 31, will now be prolonged through May 31, 2024, the United States Trade Representative said in a news release.

"The extension will enable the orderly sunsetting of the exclusions," the USTR said, while noting there were cases where additional time could be granted to "enable shifts in sourcing to the United States or third countries."

While the business group Americans for Free Trade welcomed that the extension would provide "economic relief for American businesses," it said it was "frustrated" at USTR's lack of notice, "making it difficult for businesses to plan."

The original sanctions stem from the administration of former US President Donald Trump, which imposed tariffs on $370 billion worth of Chinese products, citing unfair trade practices.

However, USTR established a process for requesting and granting exclusions from those measures.

The extensions announced Tuesday pertain to 352 Chinese products once hit by punitive duties, plus another 77 Covid-related exclusions.

Tensions between the world's two biggest economies have soared in recent years as both sides clashed on issues ranging from human rights to export controls.

Following a summit of US and Chinese presidents, Joe Biden and Xi Jinping in November, US Commerce Secretary Gina Raimondo held talks with Chinese counterpart Wang Wentao and pledged more in-person talks in early 2024.

Washington says its export curbs, which aim at reducing China's access to advanced chips critical to the development of artificial intelligence tech and cutting-edge weapons, are a national security measure.

But Beijing has dismissed those concerns, with Xi telling Biden in November that such actions hurt China's "legitimate interests."