UN chief Ban Ki-moon said Saturday that Syrian authorities have "manifestly failed" to protect civilians and called on the international community to act to stop the violence.
"The Syrian government has manifestly failed to protect civilians and the international community has a collective responsibility to live up to the UN charter and act on its principles," Ban said during a visit to Croatia's Brijuni Island as part of a week-long Balkans tour.
Ban added that he was "deeply distressed by the rising death toll and the number of people forced to flee their homes" as heavy clashes between troops and rebels raged in Syria's second city Aleppo Saturday, according to activists.
The capital Damascus was calm after a day of fierce fighting.
Ban praised the United Nations' Security Council vote a day earlier to allow a "final" 30-day mandate extension to the troubled UNSMIS observer mission charged with overseeing a peace plan for Syria.
"The unanimous vote (Friday) on resolution 2059 is a constructive sign. Now the council must redouble efforts to forge the united way forward and exercise collective responsibility under the charter of the UN," he stressed.
The UN secretary general also called on the parties in Syria, government and opposition forces alike, "to stop armed violence without any conditions".
"The extension of the UNSMIS mandate for only 30 days is a strong signal that the onus is above all on the parties, with the Syrian government in the first place who must stop the killings and the use of heavy weapons against population centres," Ban said.