Sinn Féin president Mr Gerry Adams has described the North's new electoral register as "a scandal".
He said that, according to the census figures released last month, 187,000 people who should have been on the register were missing. These individuals could be disenfranchised in May's Assembly election unless the Electoral Office took radical action.
Around 11,000 voters - nearly one in five - in Mr Adams's West Belfast constituency were wiped off the list last year. This is the first electoral register in the North to be compiled after the introduction of extensive anti-fraud measures.
Sinn Féin's political opponents have claimed it stole tens of thousands of votes at previous elections through impersonation. Mr Adams denies this. "The electoral register issued in December 2002 shows that 130,000 people across the North who were on the electoral register of June 2002 are not on this register.
"In addition, the 2001 census figures released in December 2002 show that another 57,683 people across the North eligible to be included on the register do not appear.
"This brings the total to 187,683 people eligible to be on the register who do not appear. This is a seriously-flawed registration process and a mess of gigantic proportions. It will affect supporters of all political parties but particularly those who come from a disadvantaged background."
Mr Adams outlined a five-point plan of action for the Electoral Office. He urged it to contact all those who are registered to vote that they are on the list, and then canvas those who should be entitled to vote but are absent from the register.
He said it should launch a publicity campaign to encourage those absent from the list to register. It should also establish help clinics to advise people on how to fill in the forms. The Electoral Office should also encourage first-time voters to register through issuing the forms to sixth-formers at schools and colleges. Mr Adams claimed there had been a failure to register as many as 80 per cent of first-time voters.
"We intend to have a short and sharp campaign to ensure those who want to vote have the ability to do so," Mr Adams said.