The outgoing Bishop of Bath & Wells is urging the European Union to keep a sanction on the supply of arms to Syria in place.
The arms embargo is due to expire on 31 May and EU foreign ministers are considering calls by the UK and France to ease sanctions.
Bishop Peter Price spoke of his regret over the UK Government's stance, saying that the conflict was already "dangerously over-armed".
He expressed support for the efforts of the US and Russia to bring President Bashar al-Assad's government and the Syrian opposition to the table for peace talks in Geneva next month.
The bishop encouraged the UK Government to see itself as a "custodian of a constructive approach to a diplomatic process".
He said: "That would include taking steps to ensure that the Syrian National Council plays a constructive role at the peace conference, offering support to any regional or international peacekeeping force and facilitating, ensuring access and co-ordinating the humanitarian response. This would be an entirely appropriate action for our Government to be engaged in."