UNITED NATIONS -- UN Secretary-General Ban Ki-moon on Monday welcomed the agreement announced earlier in the day by US Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrov on the terms of a nationwide cessation of hostilities in Syria scheduled to come into effect on Feb 27.

"The secretary-general strongly urges the parties to abide by the terms of the agreement," said a statement issued here by Ban's spokesman.

Earlier Monday, Kerry and Lavrov reached a provisional agreement on terms of a cessation of hostilities in Syria, where more than 250,000 people have been killed since March 2011. The two foreign ministers are co-chairs of the International Syria Support Group (ISSG) Ceasefire Taskforce formed in Munich, Germany.

"Much work now lies ahead to ensure its implementation, and the international community, the ISSG and the Syrian parties must remain steadfast in their resolve," the statement said. The ISSG, comprising the Arab League, the European Union, the United Nations, and 17 countries including the United States, Russia and China, laid the groundwork for the intra-Syria talks at a meeting in Munich in November 2015.

"Aware of the lengthy and detailed discussions that preceded this announcement, the secretary-general believes the agreement, if respected, would constitute a significant step forward in the implementation of Security Council resolution 2254 (2015)," the statement said.

"It demonstrates the commitment of the ISSG to exert influence on the warring parties to bring about an immediate reduction in violence as a first step towards a more durable ceasefire," the statement said. "It further contributes to creating an environment conducive for the resumption of political negotiations."

"Above all, it is a long-awaited signal of hope to the Syrian people that after five years of conflict there may be an end to their suffering in sight," the statement added.

The Office of the Special Envoy for Syria, Staffan de Mistura, "stands ready to support implementation of the agreement, both on the ground in Damascus and in Geneva," the statement said. "The United Nations further counts on the cooperation of ISSG members as all stakeholders jointly set the implementation mechanism in motion."