UN-Arab League joint envoy to Syria Kofi Annan said on Friday that an international conference on Syria could take place in Geneva on June 30.

He said he has been working to convene a meeting with ministers from "countries with influence" to discuss further measures and actions to ensure the implementation of his six-point peace plan.

"It is time for countries of influence to raise the level of pressure on the parties on the ground and to persuade them that it is in their interest to stop the killing and start talking," Annan said at a press conference held together with head of the UN Supervision Mission in Syria (UNSMIS) Major General Robert Mood.

Annan said the meeting would be held on June 30 "if we can get everything sorted out" and the composition and other details of the meeting are still under discussion.

He said he hoped that apart from the permanent members of Security Council, it will include governments and countries with influence on one or the other parties. He said the group should include Iran.

"I have made it quite clear that I believe Iran should be part of the solution," he said.

Annan also said he fully supported the decision of the UNSMIS to suspend their monitoring activities in Syria due to escalating violence.

Mood said the observers are currently in their team sites, conducting some administrative activities, including continuing the engagement by telephone with different parties, having some patrols to local hospitals and assessing situations.

"Whether more observers or arming observers would be relevant to the situation on the ground, I'm far from convinced that that would help the situation on the ground," he said.

Mood said the level of destruction and need for reconstruction is "beyond the classical interpretation of humanitarian aid," and he is particularly concerned about the continued military occupation of hospitals, health facilities and schools, which is preventing medical access to those in need.

He said there are civilians trapped in the combat zones and the latest attempts by the International Committee of the Red Cross (ICRC) to evacuate women, children and elderly out of in the central Homs region had "regrettably not yet succeeded."

Annan said he had approached the government directly to help release the citizens who are trapped in Homs.