(Reuters) - Mobile phone parts producer Lumentum Holdings Inc on Monday was the first U.S. company to confirm formally it was halting shipments to Huawei Technologies, following export restrictions put in place by the United States Department of Commerce.

The company, which is seen as a major supplier of Apple Inc’s Face ID technology, said it cannot predict when it will be able to resume shipments.

The Trump administration last week added Huawei to a trade blacklist, a move that bans the company from buying parts and components from American firms without U.S. government approval.

Spain’s Telefonica also said it was reviewing the U.S. order to see if it will affect its customers.

While most of the U.S. suppliers have not issued statements on their position on the Huawei ban, Bloomberg reported that Intel Corp, Qualcomm Inc, Xilinx Inc and Broadcom Inc have told their employees they will not supply to Huawei until further notice.

The companies did not respond to multiple requests from Reuters for comment.

Shares of U.S. suppliers were lower in premarket trading following a Reuters report that Alphabet Inc’s Google suspended some business with Huawei.

Lumentum said Huawei represented 18% of its total revenue in its last reported quarter. The company now expects revenue of $375 million to $390 million in the fourth quarter, down from a previous forecast of $405 million to $425 million.

Lumentum shares were down 4% in trading before the bell.