A delicate cease-fire in Syria between military forces, opposition fighters and external supporters remains in effect for a second day, despite repeated claims of breaches from both sides.
Russia blamed Turkey for nine violations since the truce began early Saturday, according to the French news agency AFP.
Syrian state media claimed "terrorist groups" fired mortars from hills close to the Turkish border into rural areas of the country's coastal Latakia province.
A senior Saudi Arabian official in turn alleged Syrian and Russian forces committed "cease-fire violations" in Syria.
"We are discussing this with (the 17-nation) Syria Support Group," co-chaired by Russia and the United States, said Saudi Foreign Minister Adel Jubeir said in Riyadh.
While many Syrians are enjoying the relative calm of a cease-fire, that quiet was broken in several towns hit by airstrikes Sunday, a day after the cessation of hostilities went into effect.
The Britain-based Syrian Observatory for Human Rights said at least six villages were targeted in the strikes. The identity of the jets was not known and it was unclear if the raids hit areas covered by the truce, which does not apply to assaults on militants from Islamic State and the al-Qaida-linked al-Nusra Front.
It was not immediately clear whether the Russian count included the same sites in the Syrian Observatory toll.
U.S.-led coalition airstrikes continued against Islamic State targets in Syria from Saturday to Sunday, focusing heavily on the IS stronghold of Raqqa.
The U.N. envoy for Syria said the first day of the cease-fire mediated by the U.S. and Russia was "quite reassuring."
Staffan de Mistura said some episodes of violence were expected after five years of conflict. But he added "the first night and first day certainly gave the impression that everyone is serious in their commitment to keep on going with this cessation of hostilities."
The Syrian opposition’s umbrella group, the High Negotiations Committee, says 97 groups have promised to take part in the cease-fire.
U.S. President Barack Obama said Saturday in his weekly address Islamic State's territory in Syria is shrinking. He said the number of fighters on the battlefield is dwindling and it has become harder for the jihadists "to recruit and replenish their ranks."
Obama said the United States is working with "partners around the world" to discredit the ideology the Islamic State uses "to radicalize, recruit and inspire people to violence."
Less than an hour before the temporary truce went into effect Friday, members of the U.N. Security council unanimously endorsed the deal. At the same meeting, de Mistura announced that if the truce largely holds and humanitarian aid access continues he will reconvene intra-Syrian peace talks in Geneva on March 7.
The co-chairs of the International Support Group for Syria (ISSG), Russia and the United States, will be responsible for addressing violations, not the United Nations.
President Obama said the United States will do everything it can to make the agreement hold.
Margaret Besheer contributed to this report from the United Nations.