Ulster Rugby is being investigated by the Planning Service over the installation of unauthorised glass panels at a new stand in the refurbishment of the Ravenhill stadium.
Last week the Belfast Telegraph revealed that Ulster Rugby had agreed to remove glass from the first floor of the west stand because of concerns voiced by residents whose homes back on to the stand.
Last night the glass had still not been removed and there was no similar pledge over glass installed on the ground floor of the stand.
Ravenhill Park Gardens resident Raymond Quinn claimed the glass on the ground floor allowed a view directly into his and his wife Kate's bedroom window.
The couple, who have children, voiced concerns over a potential lack of privacy.
Mr Quinn welcomed Ulster Rugby's assurances last week in a statement that it had instructed contractors to remove the glass from the first floor, but he said it had not been removed as yet.
Some 27 residents on the street have signed a petition against the panels.
Mr Quinn emphasised he had no objection to the new stadium, but simply said his family should have their privacy: "My family and I deserve our privacy. We simply cannot live with windows giving a view into our bedroom."
He insisted that there had been no glass in the initial plans passed by the Planning Service.
A spokeswoman for the Planning Service confirmed this and revealed that enforcement investigations had been launched into the unauthorised installation of the glass panels, adding that the construction of the new stand was being monitored.
In a statement, the Planning Service said: "Following receipt of a number of complaints, DoE Planning commenced enforcement investigations into the unauthorised installation of glass panels to the rear of the west stand at Ravenhill rugby ground.
"The glass panels do not conform to the approved drawings. DoE Planning has issued a warning letter to the landowner, advising that this constitutes a breach of planning control and should be remedied without delay."
The spokeswoman said if the glass is not removed then enforcement action may be initiated.
An Ulster Rugby spokesman said: "On January 22 the IRFU (Ulster Branch) instructed its main contractor (Gilbert-Ash) to remove the glass and replace it instead with solid panels.
"The solid panels have been ordered and work on their installation will start as soon as possible."
Planning Service officials are set to meet with architects for Ulster Rugby on Monday.
The home of Ulster Rugby at Ravenhill is undergoing a £14m transformation.
It capacity will be increased from 12,000 to 18,000 seats with the aim of creating a more family-friendly ground as well as the capacity to host a PRO12 final or Heineken Cup quarter-final match.
The original ground was opened in 1924.