New Delhi: A question mark hangs over Air India's efforts to join the global airline grouping Star Alliance, with the deadline for the national carrier expiring on Sunday.

While an airline official said that the formal induction of Air India has been "postponed by a couple of weeks", industry sources said a meeting of the Star Alliance Chief Executives' Board would take a decision on Sunday.

Air India was given a deadline of July 31 to meet all standards and criteria to join the Star Alliance network.

On Sunday, the group's Board would vote to approve or disapprove the induction of the ailing national carrier. Air India's joining Star Alliance would not be possible even if a single member airline casts a negative vote, the sources said.

Top Alliance officials had last week met Air India functionaries and senior government officials here and had termed their discussions as "progressive".

Star Alliance has also invited Jet Airways to join the grouping, along with Air India.

As part of a crucial requirement, Air India integrated its ticketing code in February to 'AI'. The earlier ticketing codes were 'AI' and 'IC' which was a remnant of the pre-merger scenario where Indian Airlines and Air India operated separately.

It also fulfilled another requirement of having the same code for domestic and international travel to ensure seamless travel.

Joining the alliance would enable the national carrier to add depth to its route network in the international sector by providing passengers last mile connectivity in foreign countries.