The United Nations (UN) children's fund on Tuesday expressed “outrage” over the killings of children in Syria by issuing a blank statement, adding in a footnote that “no words will do (them) justice”.

The statement came after a ferocious Syrian regime bombing campaign pounded the rebel-held enclave of Eastern Ghouta on Monday, killing 127 civilians, 39 of them children.

Read: The Syrian war through a child's eye

“No words will do justice to the children killed, their mothers, their fathers and their loved ones,” said Geert Cappelaere, Unicef regional director for the Middle East and North Africa.

Those words were followed by a blank page.

Unicef voiced its anger in a postscript at the end of the news release, entitled “The War ON Children in Syria. Reports of mass casualties among children in Eastern Ghouta and Damascus.”

“UNICEF is issuing this blank statement,” it said. “We no longer have the words to describe children's suffering and our outrage. Do those inflicting the suffering still have words to justify their barbaric acts?”

The UN on Monday had demanded an end to the targeting of civilians in Syria.

But on Tuesday, the Syrian Observatory for Human Rights war monitor said at least 50 civilians, including 13 children, were killed in the second day of air strikes on Eastern Ghouta.

Held by rebels since 2012, Eastern Ghouta is the last pocket of opposition-held territory around Damascus and the regime of President Bashar al-Assad appears to be preparing a ground assault to retake it.