A portion of the roof, canopy and several beams at the domestic terminal 1 collapsed after heavy rain in the Indian capital on Friday, killing one person, crushing cars and disrupting flights ever since.
The incident has put a spotlight on challenges Prime Minister Narendra Modi's government faces to overhaul infrastructure projects and has raised concerns about lax regulation and compliance issues.
The recently expanded terminal is mostly used by low-cost carriers IndiGo and SpiceJet, and has a capacity to handle 40 million passengers annually, but its closure is set to increase pressure on two other terminals from where domestic flights also operate.
A source at GMR Airports Infrastructure, which operates the airport, said "it could take few weeks, if the issue is small but very likely that it could take beyond a month if the problem is major."
"No matter how much time it takes, the terminal will not be re-opened until everything has been checked thoroughly," the person added.
GMR said in a statement that it was "too early" to provide details of when the terminal could resume operations.
Delhi airport handles 1,400 flights a day across its three terminals. Flight operations from T1 were currently limited to less than 15% of the total as they were gradually resuming after the recent expansion and refurbishment.
More than 22,000 passengers have been affected in the past three days, with around 90 flights moved to other terminals, government data shows.
On Monday, a Reuters photographer was not permitted to enter the accident site as the area has been cordoned off by authorities.
The second source said that the debris would not be removed until an inspection was complete, which was likely to take a few weeks.
IndiGo and SpiceJet said their passengers were being informed about terminal changes.
However, on Monday, two passengers told Reuters near T1 they had no information on any change in their departure terminal. "I'm running late and it will affect my timing to board my flight," said Satyam, a 22-year old student who only gave his first name.