MONTREUX, Switzerland?- UN Secretary-General Ban Ki-moon says that the peace talks for Syria, which opened Wednesday in Switzerland, face "formidable" challenges.

Ban called on the Syrian government and the opposition trying to overthrow it to negotiate in good faith.

"We know that it has been an extremely difficult path to reach this point. We have lost valuable time and many many lives. Let me not mince words, the challenges before you and before all of us are formidable. But your presence here raises hope," he said in his opening remarks.

The peace conference marks the first time the government led by Bashar Assad and Western-backed members of the rebellion have met face-to-face. But the umbrella group representing the opposition is in disarray, and the talks themselves were in question just two days ago.