India summoned the Sudanese Ambassador on Monday to register concern over the kidnapping of four Indian nationals who were abducted in Heglig, Sudan, on May 13. N Ravi, secretary (East) in the Ministry of External Affairs (MEA) asked the Ambassador to convey “India’s concern over the incident and to urgently secure the release of the four workers,” MEA officials said. “Our Ambassador is in touch with the concerned authorities in Sudan including the Ministers of Foreign Affairs and Interior Affairs. The Ministry continues to closely monitor developments,” the MEA spokesperson.added.The abducted persons have been identified as P K Abhilash from Kerala, Mohammed Aseeb Shaik from Gorakhpur, Biplab Biswas from Kolkata and Surjit Singh from Amritsar. Their Sudanese driver was also kidnapped. Officials said the Indian nationals were employed with Petro Energy Contracting Services, an Indian-owned Sudanese company that provides services to the Greater Nile Petroleum Operating Company of which ONGC Videsh is a consortium member.