Stormont politicians have been issued with a final written warning over their failure to attend Assembly questions.
In a strongly worded letter, Speaker Willie Hay said he would penalise politicians who did not turn up.
Last week seven questions were not tabled because MLAs were absent from the chamber or withdrew their question at the last minute.
Mr Hay said: "I am not responsible for ensuring that members are in the chamber. That is clearly for parties themselves and parties alone.
"I hope that all parties will make every effort to avoid a repeat of the situation last week. It is for all members and ministers to uphold all the rules and conventions and realise the seriousness of the situation."
Mr Hay acknowledged that some political parties were worse than others and said his office would be monitoring the situation closely to identify main offenders.
Last week the First and Deputy First Ministers criticised MLAs who had not turned up to ask their questions. Martin McGuinness described the situation as an absolute disgrace and urged the Speaker to intervene.
The written warning has been sent to all 108 MLAs. In it, Mr Hay said: "Members will be aware that when this issue arose in the last mandate, for a short time I ruled that members who were not in their place would not be permitted to ask questions in the chamber for two weeks. I will be monitoring the situation closely and, if it continues, I will not hesitate to reintroduce sanctions on members for not being in their places or for withdrawing questions at the last minute."
The letter, which also reminded MLAs of the importance of Question Time, noted that adverse publicity was regretful.
It said: "Ultimately this is a parliamentary institution. A level of formality and procedure is required and it cannot be approached in the casual manner adopted by some members. Given the press coverage in recent weeks, I hope all members will now realise the impact of such issues on the reputation of the Assembly to which we all have been elected."