UN Secretary-General Ban Ki-moon slammed Russia and China’s veto of a Security Council resolution on the Syria crisis on Saturday, saying it “undermines” the United Nations.

AFP quoted a statement by Ban in which he said he “deeply regrets” the failure to agree on a resolution condemning the deadly crackdown on protesters by President Bashar al-Assad.

Ban said the veto “undermines the role of the United Nations and the international community in this period when the Syrian authorities must hear a unified voice calling for an immediate end to its violence against the Syrian people.”

He added, “As Syria’s crisis deepens, bringing escalating violence and suffering to the Syrian people, the Security Council has lost an opportunity to take unified action that could help end this crisis and forge a peaceful future.”

The UN chief said the veto in the Security Council was “a great disappointment to the people of Syria and the Middle East, and to all supporters of democracy and human rights.”

The resolution vetoed earlier by Russia and China demanded that Assad resign and was backed by the Arab League. The League later called on Arab countries to shut down their embassies and consulates in Syria, and remove Syrian ambassadors from their countries.

U.S. Ambassador to the UN Susan Rice said that Washington was “disgusted” by the vetoes.

“The Security Council has been held hostage for months by two member states, at least one of which is still supplying Syria with weapons,” Rice said at the Council meeting after the vote.  France’s UN Ambassador Gerard Araud called the vetoes “a sad day for the UN Security Council, a sad day for democracy and a sad day for Syrians.”

The vetoes followed a particularly bloody night in Syria, as Assad-controlled forces opened fire on crowds in the city of Homs, killing over 400 people. Human rights groups said over the weekend that some 7,000 people had been killed in Syria since March 2011, when the uprising against Assad began.