A review has been launched by the Department of Education after it emerged that a teaching website run by a paedophile was not barred in Northern Ireland until a parent complained.
Caitriona Ruane launched the review after Samuel Kinge, 28, from Worcestershire, was jailed for a second time last month for downloading abusive images of children.
He had been running the Sparklebox teaching and parenting resource website used in thousands of schools across the UK.
Access to the site was blocked only last Monday - more than three months after Kinge's rearrest - after a parent from a Belfast primary school reported his conviction to the school, the education minister added.
SDLP MLA Conall McDevitt accused the minister of going to sleep on the issue.
Stormont education committee chairman Mervyn Storey asked: "Why was it that it took a parent to notify the school of this situation despite the fact that this information had been available since December of 2009?"
The parent had a child at Stranmillis Primary School in south Belfast.
Kinge, from Evesham, was a teacher jailed in Warwick in January 2005 for possession of child pornography.
He started Sparklebox in February 2006 having changed his name from Daniel Kinge and was arrested again last September on charges of making and possessing indecent images of children.
Worcester Crown Court sentenced him to a year in prison last month with a 15-year sexual offences banning order preventing him from using a computer unless it has a police detection programme installed.
The group which manages the IT system in Northern Ireland, C2K, became aware of issues surrounding Sparklebox last December and spoke to the regional broadband consortia in England, several of which had already blocked access to this site until they satisfied themselves that suitable safeguarding arrangements were in place.
Ms Ruane said C2K took the view that sufficient arrangements were in place to ensure the safety of users and did not therefore initially remove access to the site.
C2K's position is that their system has automatic filters in place to block any possible interactive component in the site.
She added: "I remain to be convinced that responses to this particular situation were proportionate and timely."
Her department has written to the Western Education and Library Board to instruct them to investigate how the matter was handled and make recommendations on what lessons can be learned.
SDLP education spokesman Dominic Bradley said: "There is no reason why the minister should not issue instructions today, before the outcome of any inquiry, as to what the schools internet portal C2K should do if any similar situation arises in the future.
"Websites should be blocked immediately and schools informed without delay. When it comes to protecting children, the minister should shut the door first."
© Press Association