China said Thursday it had cracked three spying plots, including one in which a public servant was lured by the “seductive beauty” of a foreign agent, urging government workers to remain vigilant against overseas threats.

Beijing has stepped up espionage warnings in recent years as relations with the United States and other Western nations have worsened. Its Ministry of State Security (MSS) said Thursday that foreign spies “have been increasingly active in infiltrating and stealing secrets from China” and were targeting public officials.

“Individual officials have caused the damaging effects of leaking secrets due to a lack of belief, a weakened sense of discipline and a loosened awareness of rules… harming national security and interests,” the MSS said.