ASTANA, Kazakhstan (AP) — Russia, Iran and Turkey — sponsors of talks in Kazakhstan between Syria and rebel factions — pledged Tuesday to consolidate the country's nearly month-old cease-fire and set up a three-way mechanism to ensure compliance of all sides.

At the conclusion of the two-day conference on Syria's nearly six-year war in Astana, the three countries said they will use their "influence" to strengthen the shaky truce, which has been in place since Dec. 30.

They did not specify how that would work, and the U.N.'s Syria envoy, Staffan de Mistura, only said that the three sides will meet soon in Astana to lay the parameters for a mechanism to reinforce the truce.

"It's going to be a challenge, it's not going to be easy," he told reporters later.

Following the declaration, read out by Kazakhstan's foreign minister, Kairat Abdrakhmanov, Syria's delegates to the Astana meeting held competing press conferences that underlined the enormous differences between the two sides.

"We don't accept any role for Iran in the future of Syria," said Mohammad Alloush, the head of the rebel delegation, insisting that all Iranian-backed foreign militias fighting alongside the Syrian government withdraw from Syria.

Syria's U.N. envoy Bashar Ja'afari, said it was "pitiful" that the opposition was criticizing one of the three guarantors who facilitated the agreement.

"The issue here is that finally we have a consensual paper called final communique or final declaration agreed upon by everybody ... this is what we care about," Ja'afari said.

Ja'afari, however, said that military operations in an area near the Syrian capital would continue despite a pledge to enforce the cease-fire "as long as there are terrorists depriving seven million people in the capital Damascus from drinking water."

The government says al-Qaida-linked militants are present in Ain al-Fijeh, which is located in the water-rich Barada Valley northeast of Damascus.

Ja'afari accused insurgents of using the water as a weapon but the rebels deny an al-Qaida-linked group is in the area, and have negotiated to include it in the cease-fire agreement.

The statement signed by the three sponsors Tuesday said the agreement in Astana paves the way for political talks to be held in Geneva at a later date, and welcomes the rebel groups' participation in the U.N. sponsored talks.

Russia, an ally of the Syrian government, and Turkey, a supporter of the opposition, had negotiated the shaky Dec. 30 cease-fire. Iran, which supports Syria, had approved it. The cease-fire greatly reduced the violence in Syria, but violations continued and the Syrian opposition and the government and its allies exchanged blame.

The meeting's final statement said the three countries "will seek through concrete steps and using the influence of the parties the consolidation the cease-fire" and agreed "to establish a trilateral mechanism to observe and ensure full compliance with the cease fire, prevent any provocations and determine all modalities of the ceasefire."

The statement said the three nations will continue their joint efforts in fighting the extremist Islamic State group and the al-Qaida affiliate in Syria. They called on the opposition to separate themselves from the al-Qaida-affiliate, a sticky point that has previously been the reason for the failure of previous cease-fire.

The rebel groups have formed close links with the group, known as Fatah al-Sham Front, on the ground. Tough fighters, Fatah al-Sham is excluded from the cease-fire according to the government, but the rebels say the truce should include all of Syria.

Astana featured a brief face-to-face meeting between the government and rebel representatives — their first since the Syrian war began in 2011 — that was quickly followed by harsh exchanges.

But the talks were largely indirect, mediated by the United Nations envoy.

After the final statement and in a briefing with journalists, Syria's opposition delegation said it is "too early to judge the outcome" of the Astana meeting, saying they are not party to the agreement and have many reservations.

"There is no consequence to statements. Our Syrian people in besieged areas do not have internet or social media to read the statements. They only know actions," said Osama Abo Zayd, an opposition representative.

He said any occupation of the Barada Valley by the government will render the cease-fire agreement void.

"We have a lot of reservations. ... Iran is still a party trying to effect forced demographic changes and sectarian changes, and it is principally responsible for the violations of the cease-fire," Abo Zayd said.

According to both Alloush and Abo Zayd, the opposition provided a paper to Russia detailing ways to monitor and enforce the cease-fire, and Russia has promised to address it within a week, in coordination with Turkey.