The senior executives held in the captivity of the anti-project group were identified as K S Choi, general manager (construction), S H Nam, T J Aan (both engineers) and D Ojha, an Oriya official, company sources said.

"The foreign nationals were in captivity since more than three hours," Jagatsinghpur Collector P K Meherda told PTI. He said efforts were on to ensure safe release of those detained, including the South Korean nationals.

Meanwhile, Posco Pratirodh Sangram Samiti (PPSS) which has been opposing the South Korean company's steel project, claimed that its activists rounded up the officials when they were undertaking survey near the proposed port site.

"The three Koreans and one Oriya officer are in our captivity. They are safe," PPSS president Abhay Sahu told PTI adding that the officials were held hostage as they deliberately entered the "restricted" area.