Sinn Fein's two ministers have told the Assembly they cannot function properly while North-South ministerial meetings are not taking place.
During question time both the Minister of Education, Mr Martin McGuinness, and the Minister of Health, Ms Bairbre de Brun, outlined the areas of cross-Border co-operation which should have been addressed but, in the absence of ministerial meetings, had not been.
Ms De Brun said the refusal of Mr Trimble to nominate her to the North-South sectoral meetings on health had hampered progress in a number of areas of agreed co-operation.
"In A & E services, for example, my staff and those of the Department in Dublin have held meetings identifying areas for enhancing co-operation in cancer services, staff training, development and exchange," she said.
Ms de Brun said "emergency planning, including cross-Border responses to road traffic accidents", also needed to be taken forward.
"The whole question of the food safety promotion board is one that needs to be examined. Clearly the work of this board is being held back because the board is not able to appoint permanent staff, continues to operate with an interim chief executive and has not been able to obtain agreement for its strategic plan," she said.
Mr Danny Kennedy of the UUP said the failure of Sinn Fein to make political progress on the arms issue was the main stumbling block for the Education Minister's non-attendance of meetings.
Mr McGuinness said that if he accepted that analysis he would be standing the Belfast Agreement on its head.
"The reality is that the work that I am involved in as Minister of Education has to be over and above all of these outstanding difficulties which exist within the process," he said.
Meanwhile, the Finance Minister said an increased effort was needed in order to spend the first tranche of European funding for the North by the end of this year.
Reporting on the last meeting of the North-South Ministerial Council on Special European Union Programmes in Dublin earlier this month, Mr Mark Durkan said that by the end of last year overall expenditure for the PEACE I programme stood at 79 per cent, while 86 per cent of funds from the INTERREG II initiative had been used.