The launch of India’s GSAT-14 communications satellite aboard a Geostationary Satellite Launch Vehicle (GSLV-D5) was called off Aug. 19 due to a fuel leak in the rocket’s second stage, a senior space scientist says.

The countdown was halted two hours before scheduled liftoff at the launch pad at Sriharikota in the southern state of Andhra Pradesh, Indian Space Research Organization (ISRO) Chairman K. Radhakrishnan confirms.

“A leak [was] observed in the UH25 fuel system of the liquid second stage during the pre-launch pressurization phase on the vehicle,” he said. Propellants were drained and the GSLV has been moved back to the vehicle assembly building to assess the cause of the leak, Radhakrishnan adds. The Indian space agency will announce a revised launch date after a detailed assessment of the fault, Radhakrishnan notes.

The three-stage GSLV stands 49 meters (160 ft.) tall, with a 414-ton liftoff weight. It has a maximum diameter of 3.4 meters at the payload fairing. It is the second launch vehicle developed by ISRO, after the Polar Satellite Launch Vehicle, which has successfully completed 22 launches in a row.

The latest attempt to launch the indigenous rocket came after a string of failures of the GSLV—four of its 10 attempted flights have ended in disappointment in recent years, most recently in December 2010.

“The postponement of today’s launch is a huge setback to ISRO. It had taken ISRO three years to organize its re-launch,” space expert Pallav Bagla says.

Propellant leaks are “highly risky” because if the leak were to ignite it could “cause huge damage to the engine,” he explains.

India is looking to increase its share of the growing commercial satellite launch market. “[The] GSLV-D5 launch is crucial for India to display its potential to develop and use cryogenic engines, which are much needed for the launch of big telecommunication satellites,” Bagla says. “It is a money-maker for India as the country can start launching satellites for other countries as well.”

India also plans to loft the heaviest variant of its GSLV, the Mk. 3, in 2014. The Mk. 3 is designed to launch communications satellites weighing more than 4 metric tons (8,800 lb.), according to ISRO officials. It also could be used for launching Indian astronauts in the future.