U.N. Secretary General Ban Ki-moon called on Syrian authorities to stop killing civilians and said potential crimes against humanity were taking place in the country.

We see neighbourhoods shelled indiscriminately, hospitals used as torture centres, children as young as 10 years old jailed and abused. We see almost certain crimes against humanity, he told reporters after meeting Austrian President Heinz Fischer Thursday.

Ban said he had read of Syrian President Bashar al-Assad's plan to hold a referendum that could lead to multi-party elections within 90 days but said the priority now had to be halting the bloodshed in an uprising against Assad's rule.

What is important at this time is that first Syrian authorities must stop killing their own people, must stop violence. This violence should stop from all sides, whether by national security forces or by opposition forces, he said.

Ban, who opened an international conference on fighting the illicit drugs trade from Afghanistan, said he would meet the foreign ministers of Russia and France in Vienna Thursday to discuss stalled U.N. Security Council action on Syria.

He called it regrettable that the Council could not agree so far on a resolution, and said: Now that is behind us. We have to look to the future.

Ban said thousands had died, 25,000 people had fled Syria, an estimated 70,000 had been displaced within the country and the numbers were rising by the day.

Lack of agreement in the Security Council does not give the government licence to continue its assault on its own people. The longer we debate the more people will die.

(Reporting by Michael Shields and Fredrik Dahl; Editing by Louise Ireland)

(This story was corrected to remove reference to killing in paragraph 2)