Alarm over China's stranglehold on critical minerals grew on Tuesday as global automakers joined their U.S. counterparts to complain that restrictions by China on exports of rare earth alloys, mixtures and magnets could cause production delays and outages without a quick solution.

German automakers became the latest to warn that China's export restrictions threaten to shut down production and rattle their local economies, following a similar complaint from an Indian electric-vehicle maker last week.

China's decision in April to suspend exports of a wide range of rare earths and related magnets has upended the supply chains central to automakers, aerospace manufacturers, semiconductor companies and military contractors around the world.