Foxconn, the troubled, China-based manufacturer of iPhones and other electronic devices, has suffered a blow to its prestige with its delisting from Hong Kong's Hang Seng stock index.

Tuesday's action is the latest in a series of setbacks for the world's largest electronics subcontractor, which also assembles Apple iPads, Amazon Kindles, Nokia smartphones and other products at its sprawling factories in Shenzhen.

A series of highly publicized suicides last year called attention to working conditions at the Taiwan-owned company, which employs about 1 million people in China. Last month, three workers were killed and 15 injured in an explosion at a Foxconn subsidiary in the southwestern city of Chengdu.

Hang Seng officials did not explain specifically why they stripped Foxconn of its blue-chip status. However the company has been hurt by rising labor costs in southern China and last year reported a net loss of almost $220 million on revenue of more than $6.6 billion.