Airport Metro operations will be suspended indefinitely from Sunday for the inspection and repair of "serious" construction flaws found by Reliance Infrastructure, which operates the high-speed line.
Officials at Delhi Airport Metro Express Pvt Ltd (DAMEPL), a subsidiary of Reliance Infrastructure, did not, however, specify the time it will take to rectify the faults.
The 22.7-km line is the only corridor run on a public-private partnership by Delhi Metro Rail Corporation (DMRC), which built it.
The line connects New Delhi Railway Station with IGI airport's Terminal 3 and Dwarka Sector 21, and has a daily ridership of about 20,000.
The trains are supposed to run at 105 kmph but the speed has been dropping these last three weeks, to as low as 15 kmph on some stretches.
Sources said Reliance engineers noticed major technical defects in the civil structure in March.
"More than 250 locations were found to be critically affected," they said.
"We will carry out a joint inspection with DMRC and a private consultant in the next few days to identify the extent of damage and the reason behind it. We are not sure if the faults are due to design fault or poor workmanship," a source said.
A DAMEPL team made a presentation on the faults at a meeting chaired by urban development secretary and DMRC chairman Sudhir Krishna on Monday.
"We have a meeting on Saturday with all stakeholders to discuss the issue," Krishna said.
"We will ask the concessionaire to tell us the date by which they'll be able to resume services," said a DMRC spokesperson.