Tusk said the EU's 27 leaders, meeting separately from British Prime Minister Theresa May, would also discuss a statement of intent on future relations with Britain, which is to be announced along with the Brexit divorce deal.
Speaking to Al Jazeera, Thom Brooks, professor and dean at Durham University in the United Kingdom, said he "can't believe" Britain is faced with such alarming International Monetary Fund reports with only six months until Brexit.
The issue has been seized upon by populist leaders like Hungary's Prime Minister Viktor Orban and Italian Interior Minister Matteo Salvini as a campaign issue ahead of next May's European Parliament elections. So that's why we are cautiously optimistic that we will get a deal.
"I think this is going to be at the core of the debate in Salzburg".
Hunt defended May's Chequers proposals, which have been roundly attacked by his predecessor, Boris Johnson.
"Unless we do that. much of the point of Brexit is nullified".
May blasted Johnson for using "completely inappropriate" language when he described her Brexit blueprint as putting Britain in a "suicide vest".
EU Council President Donald Tusk said on Tuesday an extra European summit in November may be necessary to clinch a Brexit deal with the United Kingdom, warning that failure remains possible.
But the risks are that the PM can not say for certain what the final deal will look like - and some Brexiteers were already determined not to vote for it, she added.
The news comes after Michael Gove, the Environment Secretary, said over the weekend that an independent United Kingdom and its elected future leader could "choose to alter" the nation's relationship with the Brussels bloc after Brexit.
The Foreign Secretary became the first British minister to openly deliver a speech in Japanese.
Shadow Brexit secretary Keir Starmer said no-deal would be "catastrophic" and people were "too casual about it".
However, the prediction is based on Britain sealing an European Union divorce deal and transition period by the end of the year.
Supporters of Brexit, who admit there may be some short term instability, say some British ministers and business chiefs are spreading scare stories about the impact of a "no-deal" Brexit in an attempt to rally support behind May's plans.
He ruled out extending the negotiation process - Britain is due to leave at the end of March 2019 - saying such a move would effectively allow the European Union "to dictate when Britain will leave".
The government is set to publish its detailed immigration proposals in the coming months, which is widely expected to be a general toughening of stance on controlling the numbers that come into the country in line with the Conservative party's target to reduce migration.
Before leaving for Brussels, the Tánaiste said he would "be making very clear our continued strong support for Michel Barnier, welcoming his approach on efforts to de-dramatise the backstop aimed at agreeing the text of the Protocol on Ireland and Northern Ireland".