Secretary-General Ban Ki-moon says Iran is a very important regional power that can play a major role in helping end the Syrian conflict and should be allowed to participate in next month's peace conference in Switzerland, the Associated Press reports.

Lakhdar Brahimi, the UN-Arab League Syria envoy, said Friday the United States is blocking Iran's participation.

The UN chief said Monday he plans to issue invitations before the end of December to the Jan 22 peace conference and expressed hope that "the question of Iran's participation is resolved soon."

The UN chief said "negotiations will be difficult, but without them there is only bloodshed and despair on the horizon."