Northern Ireland being run by 'Civil Service' after Secretary of State's resignation
Michelle O'Neill criticised the departing Northern Ireland Secretary Brandon Lewis as having "shamefully placated the DUP".
Concern has been expressed following the resignation of the Northern Ireland Secretary that the region is now being run by the civil service.
Ulster Unionist leader Doug Beattie described the situation as "as bad as it gets".
He said the resignation of Brandon Lewis left Northern Ireland without a Secretary of State, while the Stormont Assembly remains collapsed.
Mr Lewis announced his resignation early on Thursday, tweeting a copy of his resignation letter in which he told the Prime Minister that he had "given you, and those around you, the benefit of the doubt".
"We are, however, now past the point of no return. I cannot sacrifice my personal integrity to defend things as they stand now. It is clear that our Party, parliamentary colleagues, volunteers and the whole country, deserve better," he said.
Mr Beattie told the BBC: "We're spectators here looking at what's going as this omnishambles presents itself to us.
"We have no proper functioning government in the UK, we have no Secretary of State, we have no Assembly and we have no Executive and we are being run by the civil service now as it stands, and if Northern Ireland or anywhere else in the UK were to have a major incident, I doubt we could even get the COBR committee to come together to be able to create any form of response."
Sinn Fein Stormont leader Michelle O'Neill has criticised the departing Northern Ireland Secretary Brandon Lewis as having "shamefully placated the DUP".
"Brandon Lewis abandoned any pretence of acting with the 'rigorous impartiality' required of him under the Good Friday Agreement," she said.
"He has shamefully placated the DUP by giving them political cover in denying the electorate the democratic representation they are entitled to.
"His actions are preventing ministers from using £435 million to support workers and families struggling with the rising cost-of-living crisis, agreeing a three-year budget and putting an additional billion pounds towards fixing our health service.
"He has failed victims and survivors by tearing up the Stormont House Agreement agreed by the two governments and political parties to deal with the past.
"He has undermined the Good Friday Agreement and political stability, and his actions gave us a daily reminder why those with no mandate or votes here will only ever act in their own political interests, and not ours."
Meanwhile, prominent victims campaigner Raymond McCord welcomed the resignation of Mr Lewis.
The former Secretary of State attracted the ire of victims' groups over his proposed legislation to deal with Northern Ireland's troubled past.
The Northern Ireland Troubles (Legacy and Reconciliation) Bill offers an effective amnesty for Troubles crimes for those who co-operate with an information body.
Mr McCord said: "He (Mr Lewis) has betrayed the victims of the Troubles with the Legacy Bill that gives an amnesty to murderers.
"Brandon Lewis decided to reward the murderers with amnesties for the murders they committed, and punish the victims and their families by ensuring all routes to justice and even civil cases are closed down.
"He insulted all victims by claiming it would help us. He certainly will not be missed by victims."