Northern Ireland parties divided over who should take decisions in absence of Stormont Executive after incinerator ruling
Arlene Foster has said London must now take key decisions for Northern Ireland after the Court of Appeal decision.
The DUP leader said the political situation was "not acceptable and cannot be allowed to continue".
"Key public services such as schools, hospitals and roads are being unfairly impacted.
"Four out of the five main parties would form an Executive today. In the absence of an Executive, decisions must be made in London."
Mrs Foster said she had welcomed the government's statement a week ago that it would "take whatever steps necessary to provide good governance".
"I told the Prime Minister on Monday that it is now time to follow those words with actions," she commented.
Mrs Foster continued that civil servants "cannot be left in this limbo".
"On the back of this judgment, we will again be pressing the Government to take decisions. Sinn Fein's surrender of power and boycott of the House of Commons, Assembly and Executive cannot be allowed to cause further chaos in Northern Ireland," she added.
Sinn Fein MLA Declan Kearney said the ruling was a victory for local residents and the Good Friday Agreement.
"Approval should never have been granted for this facility in the first place given the widespread opposition and concerns over the safety of residents," he commented.
Mr Kearney said the decision "signals the importance of re-establishing the power-sharing institutions in a way that is consistent with the Good Friday Agreement".
"That means dealing with the equality and rights issues at the heart of the crisis and both governments fulfilling their responsibility as co-guarantors of the Good Friday Agreement when the British-Irish Governmental Conference finally meets later this month."
North Belfast SDLP MLA Nichola Mallon appeared with 'No Arc21' campaigners and residents after the court's decision.
She welcomed the ruling and said the political vacuum could no longer continue.
"If the crisis in our health service and education system isn't motivation enough for Sinn Fein and the DUP to try to overcome their differences and form an Executive, this ruling should be. The dangerous drift they have put us all in for the past 18 months cannot continue politically, economically and legally."
Ulster Unionist MLA Steve Aiken said: "I congratulate all those who stood firm in their opposition to the Hightown Incinerator. It demonstrates the power the public can have."
Alliance Party leader Naomi Long welcomed the ruling and said that Secretary of State Karen Bradley's "unwillingness to take decisions" was now "completely untenable".
She called on Mrs Bradley to convene all-party talks with an independent mediator without delay.
The Becon Consortium which had hoped to develop the incinerator called the ruling a "disappointing setback" but said they remained committed to the project.
They added that the decision-making vacuum here was hurting inward investment and job creation.
They called for an alternative form of local decision-making for the incinerator and other infrastructure projects "stuck in limbo".
Retail NI chief executive Glyn Roberts said millions would now be wasted unless the Stormont Executive reconvened.
"The people of Northern Ireland deserve better than a 'care and maintenance' administration and need to see ministers making decisions again," he commented. "This situation cannot continue any longer."
Confederation of British Industry NI director Angela McGowan called the ruling "extremely concerning" for both the public and private sectors and called for local civil servants to be given powers to "remove this handbrake" on economic and social progress.
David Fry of the Construction Employers Federation said the construction industry was now on the brink of "complete paralysis".