Having enrolled a population of 20 crore for the unique identity Aadhaar cards across the country in the last couple of years, the Unique Identification Authority of India now targets to enrol another 40 crore in the next couple of years.

"We have enrolled 20 crore so far. We have been given a mandate to enrol another 40 crore, which we hope to do in the next couple of years. Along with that the National Population Registry (NPR) will also do the enrolment and cover the rest of the population," UIDAI Chairman Nandan Nilekani said in Hyderabadon Tuesday.

He expressed hope that in a "reasonable amount of time" they should be able to cover the entire country.

The UIDAI was working very closely with the Registrar General of India in this regard, Nilekani told mediapersons after a high-level meeting with Andhra Pradesh Chief Minister N Kiran Kumar Reddy.

"Both Aadhaar and NPR are complementary...both processes are working together on this. NPR is mandatory while Aadhaar is voluntary. However, if you enrol through NPR you will also get Aadhaar. Now everything is properly aligned," he added.

He said a series of Permanent Update Centres would be set up for carrying out corrections in the Aadhaar cards and the UIADI was working with the state governments on it.

On the delay in delivery of Aadhaar cards, Nilekani said there was a challenge earlier because of some time lag.

"But we have caught up in the last couple of months," he said.

He cited AP's case where 4.32 crore cards have already been delivered out of the 4.5 crore generated.

Incidentally, AP was leading all the states in the country in Aadhaar enrolment with 5 out of 20 crore so far.

"We have re-started the process (of enrolment)...we will go full speed and our goal is that in the next few months it should be fully saturated. We have to get our full speed up but we hope to do that very soon," Nilekani added.