India's first exploratory mission to moon Chandrayaan-1, scheduled for launch on April 9, has been deferred, a top space agency official said here on Tuesday.

"As a number of pre-launch tests have to be conducted, it is difficult to meet the April 9 deadline," Indian Space Research Organisation (ISRO) Chairman G Madhavan Nair told IANS over phone.

"The mission payload has 12 instruments. We will decide on the next launch date by this month-end after a review meeting," he said.