US diplomat Dr Richard Haass has made one last desperate plea to both sides of the community in Ulster to cut a deal on his return to Belfast for crucial talks on flags, parades and the past.

Dr Haass and Professor Meghan O’Sullivan flew back from the United States on Saturday morning for one last round of talks on the province’s most divisive issues.

They have warned that failure to reach agreement could jeopardise the gains made since the Good Friday Agreement.

Former US envoy Haass warned: “At some point political leaders have to decide whether they would rather have this agreement or not to have an agreement.”

The American pair aim to conclude discussions and launch a deal on Monday afternoon according to the Belfast Telegraph.

They were invited to Northern Ireland last summer by Assembly leaders Peter Robinson and Martin McGuinness to chair the talks and reach an agreement by the end of the year.

Dr Haass told the paper: “We have decided to return to Belfast in a final effort to help Northern Ireland’s political leaders reach agreement. We are not certain we will succeed, but we are certain that the consequences of either success or failure are so great that we must spare no effort to see that the talks end in consensus.

“It will not, however, be the two of us who make this decision. We will do all we can, but the choice is up to the parties, guided by their understanding of what Northern Ireland’s people desire and deserve. No outsider can ever want agreement more than insiders do.”

In an article for the Belfast Telegraph, Haass and O’Sullivan said they will put the onus on local politicians to move forward.

They wrote: “Urgency must be the order of the day. The gains made over the past decade-and-a-half can be lost, and even if they are not, much more needs to happen before peace and a shared future are assured.

“An agreement from these negotiations would not solve all the remaining problems, but it would dramatically increase the odds that Northern Ireland begins to live up to its potential. The opportunity should be seized while it still exists.

“But there is as yet no agreement and no certainty one will emerge.”

Flags remain the most contentious issue with the US pair proposing that all council headquarters, nationalist as well as unionist, should fly the Union flag on designated days.

They added: “The divisions over the draft text are many and deep. The reality is that no party in a diverse democracy can have all it wants.

“Compromise is essential. What matters is whether Northern Ireland would be better off with this agreement. We believe the answer to that question is yes - a resounding yes.”