It comes after former US diplomat Dr Richard Haass, who chaired talks between Northern Ireland's five main parties on a range of contentious issues, told UTV he was "somewhat frustrated" that a deal had not been struck before the end of 2013.Dr Haass seemed to indirectly blame unionists for showing a lack of leadership.Speaking on Friday, DUP leader Mr Robinson said he hopes all parties will now sit down and take another look at the issues which plagued the negotiations."Always remember that the responsibility did not lie with Richard Haass therefore he is not a failure - the political parties failed," said the First Minister."They have to roll up their sleeves and renew the work until they find agreement."The US team of Dr Haass and Dr Meghan O'Sullivan were brought in by Peter Robinson and Martin McGuinness in an attempt to resolve issues surrounding flags, parades and the past in Northern Ireland, but after seven draft proposals an agreement was not reached.Richard Haass said two of the Executive parties - namely Sinn Féin and the SDLP - had backed his document, but the DUP, UUP and Alliance had not."Two parties endorsed the agreement and three parties did not," he explained. "Two of them are Unionist and one was Alliance."I believe that all parties are in a position that there is more than enough in the agreement that they should be able to point to it and make the case exactly why it is worth their support."Giving her response, Naomi Long of the Alliance Party said they had given Haass a "green light ... on the past", an "amber light on parades" and a "red light on flags".She said: "I said we wouldn't go into these talks to cook fudge and we wouldn't sell fudge. "However the proposal on flags was fudge to make a lack of deal more palatable to the public. During the talks, Unionists refused a deal on flags on lampposts and Nationalists refused a deal on flags on Council and Government buildings. "We wanted to see the issue of flags finally resolved across the board."Mike Nesbitt, UUP leader, said: "The Ulster Unionist Party remains committed to a positive outcome in these three areas of parades, flags & emblems and dealing with the past. "This means ensuring that victims are not disrespected, the rule of law is not disregarded and society is presented with a positive future."Meanwhile talks chairman Dr Haass has also confirmed that his involvement in Northern Ireland is at an end - however he believes the talks remain a "living process". He continued: "At the end of the day, leaders have to lead and we believe that this was a good agreement. Just to be clear, it was not my agreement or Meghan O' Sullivan's agreement."