Releasing findings of its survey, Janaagraha Centre for Citizenship and Democracy said in addition to 22 percent voters requiring deletion, addresses of 11 per cent electorates were not found.
Earlier this month, the Chief Electoral Officer (CEO) of Delhi had admitted in the Delhi High Court that there were mistakes in the electoral list issued by it for the upcoming polls.
The NGO said about 33 percent names on the voters list may need to be deleted and that it has gross errors which could expose the system to risk of bogus voting. The city goes to polls on February 7.
Elaborating about the errors in the voters list, the NGO said 22 per cent names requiring deletion are those who have shifted out of Delhi or may have died or lodged in prison.
The poll panel, in its reply to a petition alleging presence of bogus voters in the national capital said that it was rectifying the mistakes and was also trying to identify the persons who caused the error.
Janaagraha Centre for Citizenship and Democracy said the survey was carried in eight constituencies in Delhi which suggested that names of about 42.50 lakh voters need to be deleted.
According to the survey, maximum of 38 per cent errors in the voters list was found Sangam Vihar while least was in Rohini with 16 per cent.
Speaking on the findings, Janaagraha coordinator Srikanth Visawanathan said, "The voters names on the list with errors like shifted, names repeated and deceased should be deleted and the other 11 per cent of voters whose addresses were not found are the potential names for deletions."
He said the errors could potentially impact electoral outcomes if one were to go by the thin margins of victory in many seats in 2013 assembly elections.
"The errors expose system to risk of bogus voting and secondly it raises questions on the legitimacy of electoral outcomes," he added.
Explaining the cause of such errors, the NGO said in the urban cities across countries a very high rate of migration takes place in both within same city and two different cities.
At the same time the rate at which names are added in the voters list is much faster than the rate at which names are deleted.