The United Nations, Secretary-General Ban Ki-moon sharply criticized the Syrian government for the persistent attacks on civilians and demanded it keep its pledge to halt all military operations, Reuters report says.

"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."

He suggested the latest killings were tantamount to a violation of U.N. Security Council demands that Damascus move toward a ceasefire.

"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," the statement from Ban's press office said.