Leaders of the rebellion against Syria's President Bashar Assad are due to join a conference in Britain designed to focus minds internationally on planning for political transition in the Middle Eastern country.
The two-day conference being held behind closed doors at Wilton Park in West Sussex will bring together officials, experts and academics, including representatives of Arab states and multilateral agencies, as well as leaders of the opposition Syrian National Coalition.
In a Twitter message about the conference, Foreign Secretary William Hague said: "Assad's departure from power is inevitable. Vital that international community plans ahead for the day after in Syria."
A Foreign Office spokesman said: "The UK's objective is to galvanise international thinking and planning on a Syrian-led political transition.
"We're doing everything we can to bring an end to the violence in Syria and achieve a genuine political transition."
Syrian experts and academics are expected to share their thinking on post-conflict stabilisation and to discuss options for the international community to be ready to support a future Syria.
The meeting is intended to support efforts to understand what kind of challenges Syria will face in transition and how the international community can provide support to a future transitional authority to overcome these challenges.
No UK Government ministers are expected to attend the conference and participants are not expected to speak publicly about their discussions.