United Nations: U.N. Secretary-General Ban Ki-moon sharply criticized the Syrian government on Friday for its latest attacks on civilians and demanded that it keep its pledge to halt all military operations, Ban's press office said in a statement.

"(Ban) strongly condemns the latest escalation of violence," the statement said. "He deplores the assault by the Syrian authorities against innocent civilians, including women and children, despite the commitments by the Government of Syria to cease all use of heavy weapons in population centers. The 10 April timeline to fulfill the Government's implementation of its (ceasefire and troop withdrawal) commitments, as endorsed by the Security Council, is not an excuse for continued killing," it said.

At least 27 Syrian soldiers, rebels and civilians were killed in violence on Friday, opposition activists said, four days before an April 10 deadline to stop the use of heavy weapons and withdraw troops from towns agreed by President Bashar al-Assad as part of a U.N.-backed peace plan.

U.N.-Arab League envoy Kofi Annan has said the government and opposition must stop fighting at 6 a.m. local time (0300 GMT) on April 12, if Damascus meets its deadline 48 hours earlier to pull back troops from cities and cease using heavy weapons.

"The Syrian authorities remain fully accountable for grave violations of human rights and international humanitarian law," Ban's statement said. "These must stop at once. The Secretary-General demands that the Government of Syria immediately and unconditionally cease all military actions against the Syrian people," it said.

The U.N. Security Council, including China and Syria's staunch ally, Russia, on Thursday unanimously endorsed the deadlines for an end to the Syria conflict and warned Damascus that it would consider "further steps" if it failed to live up to its commitments.