"If the amalgamation plan is not changed and our issues are not resolved, we will take the matter to court," said KR Chidambaram, convenor of joint action committee, a body of the eight unions opposing the merger.
The decision by the corporate affairs ministry on the matter is expected to come in the next two weeks, according to a government source.
Meanwhile, apart from a few changes like merging the ticket counters at the Mumbai and Delhi airports, the new livery and logo used in the new flights and the new website, the formal announcement of a fully merged entity is yet to come.
There was a hearing before the corporate affairs ministry on 31 July in which Indian Airlines' unions like Indian Airlines' Commercial Pilots' Association, All India Aircraft Engineers' Association, Indian Aircraft Technicians' Association, Indian Airlines' Officers' Association and Air Corporation Employees' Union filed their objections relating to issues like career progression and seniority issues.
"We are worried about the virtual take-over of Indian Airlines by Air India. We do not have our own chairman and managing director, our headquarters have been shifted to Mumbai from Delhi," said an IPCA member.
"The name of the airline has also changed as a result of which Indian Airlines has completely lost its identity. We want a clear exit policy in terms of compensation in case the merger fails," he added.
When contacted Minister of Corporate Affairs Prem Chand Gupta said, "The hearing is on and our effort is to complete the process within the next two weeks. All the stakeholders including the labour unions will be given opportunity according to the provisions of the Companies Act and after analysing the facts and the provisions of the law a decision will be taken."
The Air India management, however, said the merger was well on track and the legal issues would be settled soon.
"Our lawyers have made submissions stating that the amalgamation scheme itself says that all the issues relating to manpower will be taken care of," an Air India source said.