The U.N.'s Syria envoy says delegates will begin arriving in Geneva Wednesday for "substantive, deeper" talks between the Syrian government and opposition representatives set to begin on March 14.

Staffan de Mistura says the talks will once again be "proximity" talks — meaning indirect talks with the parties in separate rooms and the envoy shuttling between them.

He says the talks are expected to last for about 10 days before breaking up for a recess.

Speaking at a press conference in Geneva, de Mistura said a cease-fire in Syria now approaching two weeks is still holding "by and large," and was open-ended as far as the U.N. was concerned.