The United Nations Security Council voted unanimously Saturday to allow deployment of an advanced team of U.N. monitors in Syria.
The resolution condemned widespread violations of human rights by Syrian authorities as well as armed rebels.
The resolution called upon "all parties, including the opposition, immediately to cease all armed violence in all its forms."
The resolution also declared the intention to establish a full mission in Syria once the ceasefire has been established and the fighting is ended.
U.N.-Arab League special envoy Kofi Annan's six-point proposal on Syria calls for an end to violence, access for humanitarian agencies to provide relief to those in need, the release of detainees, and the start of inclusive political dialogue that takes into account the aspirations of the Syrian people.
Meanwhile, Secretary General, Ban Ki-moon said the number of monitors would be increased to 250 in coming days and called for a greater role and free movement to the UN observers in all violence stricken parts of Syria.
After vetoing previous council resolutions, Russia and China, approved sending a team of 30 unarmed UN monitors to oversee the implementation of the fragile ceasefire. Twice before, they blocked resolutions condemning Syrian President Bashar al-Assad's attacks on protesters.
However, the Russian representative made it clear that Russia could support only limited U.N. action in Syria.
"Out of respect for the sovereignty of Syria we have cautioned against destructive attempts at external interference or imposing any kind of illusory fixes," the Reuters quoted Ambassador Vitaly Churkin saying.
Russia pointed to the precedent of the U.N. resolution on Libya last year authorising civilian protection that turned into a NATO-sponsored regime change.
Earlier the U.S.-drafted text of the resolution was diluted to accommodate the Russian suggestions which "called upon" Syria to comply with the resolution and restrained from "demanding" to implement it.
French Ambassador Gerard Araud also expressed doubts on the new-found unity at the Security Council.
"Our consensus is fragile," the Reuters quoted Araud as saying.
Meanwhile, Syrian Ambassador Bashar Ja'afari accused the opposition of 50 violations of the truce since its implementation on Thursday. And the activists accused Syrian forces of continued shelling in Homs and in Aleppo killing 20 people on Saturday.
The violence in Syria, which began in March 2011 has claimed over 8,000 lives, mostly civilians, and displaced tens of thousands.