WASHINGTON—Saudi Arabia has manufactured with Chinese assist a facility for extracting uranium yellowcake from uranium ore, an advance in the oil-loaded kingdom’s generate to master nuclear technological know-how, according to Western officers with expertise of the web-site.

The facility, which has not been publicly disclosed, is in a sparsely populated area in Saudi Arabia’s northwest and has lifted issue among the U.S. and allied officers that the kingdom’s nascent nuclear method is shifting ahead and that Riyadh is retaining open the selection of developing…