"They (Star Alliance) just conveyed that our candidature has been put on hold following a meeting of the chief executive's board on Sunday," Air India spokesman Kamaljeet Rattan told AFP from New Delhi.

"We have in our possession a letter from the project manager at Star Alliance confirming that we have met all the minimum joining requirements, so we don't know why this decision has been taken," he said.

State-run Air India was given a deadline of July 31 to meet a lengthy list of requirements to join the grouping, which has 27 members that carry more than 600 million passengers a year.

Star Alliance chief executive Jaan Albrecht said: "With the collective decision to put the integration efforts on hold today we aim to contribute to Air India's flexibility to concentrate on its ongoing strategic orientation.

"In this process our member carriers will continue to provide assistance to Air India wherever required."

Star Alliance could not be reached by AFP immediately for comment.

Rattan said the airline had met the stipulated criteria, barring "a few components" that would be implemented before it joined the Alliance.

He said membership of Star Alliance, whose members operate 21,000 flights a day to 181 countries, would help boost Air India's profile.

The struggling carrier is waiting for approval of a five-year turnaround plan, including a government cash injection and a new business plan that would increase its fleet size, cut routes and set up network hubs.

The Indian government pumped about eight billion rupees ($178 million) into the airline in the financial year 2009-10 and expects to put in another 12 billion this year on condition the company cuts costs.

The restructuring plan is currently under review.

Private airlines such as Jet Airways, Kingfisher and low-cost rivals like Indigo and SpiceJet have replaced Air India as a preferred airline in recent years.

Copyright AFP (Agence France-Presse), 2011