BEIJING is delaying approval for carmaker BYD to build a plant in Mexico amid concerns that the smart car technology developed by China's biggest electric-vehicle maker could leak across the border to the US, reports London's Financial Times.

BYD first announced plans for a car plant in Mexico in 2023, along with intentions to make cars in Brazil, Hungary and Indonesia. It said the Mexican plant would create 10,000 jobs and produce 150,000 vehicles a year.

But domestic automakers require approval from China's commerce ministry to manufacture overseas and it has yet to give approval, according to two people familiar with the matter.

Authorities feared Mexico would gain unrestricted access to BYD's advanced technology and knowhow, they said, even possibly allowing US access to it. "The commerce ministry's biggest concern is Mexico's proximity to the US," said one of the people.