People are entitled to feel bewildered and angry that the UN Security Council seems unable to respond to the worst crisis of the 21st century.

Jolie is a UN special envoy for refugees.

"It is shameful that even the basic demand for full humanitarian access has not been met," she said ahead of Sunday's four-year anniversary of the first Damascus protests that led to the Syrian civil war.

"And it is sickening that crimes are being committed against the Syrian people on a daily basis with impunity," Jolie added.

Governments must overcome their differences to reach a political solution to the Syria conflict and to bring human rights violators to justice, she said.

Jolie finished off her statement by saying: "I appeal for urgent steps to demonstrate that the international community is serious about accountability in Syria: to show that we will not turn a blind eye to war crimes, and that we will not fail refugees, the displaced, and the survivors."