Endeavor's leak was detected near the Ground Umbilical Carrier Plate, which is attached to the external tank at its intertank area. -- PHOTO: NASA

The launch had been scheduled for 7.17am (7.17pm Singapore time) from Cape Canaveral in Florida. Now the earliest opportunity for the shuttle's liftoff will be on June 17, officials said.

The crew's commander, Mark Polansky, wrote on the micro-blogging website Twitter that his crew would await further word from Nasa chiefs on how to proceed.

'What happens now? We work 2 a Wed launch while senior management meets to decide on the plan. My crew stays in quarantine at KSC (Kennedy Space Center) for now.' The leak in a venting system was detected near the Ground Umbilical Carrier Plate, which is attached to the external tank at its intertank area, the National Aeronautics and Space Agency said in a statement.

The system is used to carry excess hydrogen safely away from the launch pad at Nasa's Kennedy Space Centre in Florida. 'This is NOT a shuttle problem, but a pad one,' Mr Polansky stressed.

Shuttle managers have set a meeting for 2pm on Sunday (2am Singapore time) to discuss the repair options and Endeavour's launch attempt opportunities.

It will now take the space agency 24 hours just to empty Endeavour's external tank, which contains some two million liters of liquid hydrogen and oxygen.

But officials said the new target date of June 17 may also present a conflict as Nasa has scheduled for that day the launch of the Lunar crater observation and sensing satellite, which is due to lift off on top of an Atlas V rocket from Cape Canaveral Air Force Station, Florida.

If a launch then proves unattainable, Nasa has said the only next available blast-off date would July 11 at the earliest. -- AFP