Geneva, Aug 18 (IANS): The UN's special envoy to Syria said here he hoped substantive Syrian peace talks involving representatives of President Bashar al-Assad's government and a unified opposition would take place between the months of October and November.

Staffan de Mistura on Thursday said in a press conference here that there may eventually be an opportunity in October, in Riyadh or another place, for the opposition to "take stock of the realities on the ground" and create a joint platform for negotiations with the government, Efe news reported.

With respect to the Syrian government, De Mistura said he hoped Russia, Iran and other parties with some influence over al-Assad would help ensure that he starts a "genuine, direct negotiation with whatever (opposition) platform comes out".

De Mistura said he expected the next official round of Syrian peace talks to take place shortly before the UN General Assembly in mid-September, although he predicted those negotiations would focus on the agenda for the real, substantive talks later in the year.

This will be preceded by Syrian de-escalation talks involving guarantor powers Russia, Iran and Turkey that are scheduled for Astana, Kazahkstan, probably in late August, followed by September 2.

De Mistura noted that there would only be a short period between the Astana talks and the General Assembly, where he said a high-level discussion may take place about next steps in Syria.

The UN special envoy for the Syria crisis said he expected that between now and October there would be a stepped-up struggle to liberate the Syrian cities of al-Raqqa and Deir al-Zor from the hands of the Islamic State.