Shri M.K. Ramamurthi, the learned counsel for the peti tioners, has placed reliance on Sub Section (1) of Section 13 of the ONGC Act and Clause (2) of Regulation 3 of the Regulations which provide as under: "Section 13(1): Subject to the provisions of this Act, every person employed by the existing organisation immediately before the date of establishment of the Commission shall, on and from such date, become an employee of the Commission with such designation as the Commission may determine and shall hold his office or service therein by the same tenure, at the same remuneration and upon the same terms and condi tions as he would have held the same on such date if the Commission had not been established and shall continue to do so unless and until his employment in the Commission is terminated or until such tenure, remuneration and terms and conditions are duly altered by the Commission: Provided that (a) the tenure, remuneration and terms and conditions of service of any such person shall not be altered to his disadvantage without the previous approval of the Central Government; (b) any service rendered in the existing organisation by any such person shall be deemed to be service under the Commis sion; and (c) all persons employed by the Commission on the date of 162 its establishment, who, immediately before such date.