GENEVA (AP) — The U.N. envoy for Syria wrapped up a fifth round of talks between opposition leaders and the government on Friday, pointing to "incremental" progress while acknowledging no peace deal is foreseeable as the country enters its seventh year of war.

After eight days of talks in Geneva, Staffan de Mistura says negotiators appeared "keen" on taking up a new round, but added he wouldn't announce a new start date before consulting with the organization's Security Council and secretary-general.

At news conferences in recent days, the two main delegations traded accusations of terrorism.

De Mistura said substantive matters were discussed with professionalism but declined to specify, other than listing the initial broad agenda points of governance, elections, a constitution and fighting terrorism.

He cautioned against dismissing or underestimating the "hard" work undertaken by all sides in Geneva saying that such negotiations are necessary to set the stage for a real peace process.

"It is clear we are not there yet," he told reporters, citing challenges on the ground.

He voiced concern over the violations of a ceasefire agreement which Russia, Iran and Turkey had brokered and committed to guaranteeing.

Fighting intensified over the past two weeks in Syria with insurgent groups launching wide offensives on parts of the capital Damascus, Assad's seat of power, and the central province of Hama where rebels captured several villages and got close to the provincial capital that carries the same name.

Syrian troops launched a counter-offensive and captured most of the areas.

De Mistura urged the three guarantor nations, which will hold their next meeting in Tehran, to "revitalize the ceasefire" that was borne out of diplomatic efforts in Astana, Kazakhstan.

He said: "We really mean it: a successful work in Astana on the ceasefire reinforces Geneva and vice-versa."

The mediator declined to comment on rumors that his mandate may be coming to an end.

Bassem Mroue in Beirut and Dominique Soguel in Basel, Switzerland, contributed to this report.