The administration of U.S. President Joe Biden is turning up the heat on China's top sanctioned chipmaker by cutting off its most advanced factory from more American imports after it produced a sophisticated chip for Huawei's Mate 60 Pro phone, three people familiar with the matter said.

Late last year, the U.S. Commerce Department sent dozens of letters to U.S. suppliers to Semiconductor Manufacturing International Corp. (SMIC), suspending permission to sell to its most advanced plant, said two people familiar with the matter who requested anonymity because they were not authorized to speak publicly about the matter.

While many companies had already stopped selling to SMIC South, as the unit is known, the letters halted millions of dollars worth of shipments of chipmaking materials and parts from at least one supplier, Entegris, one of the people said.