UN mediator Staffan de Mistura wants his next consultations on the conflict in Syria to include “all those with influence,” but has yet to complete a list of participants, a UN spokesman said Tuesday, according to AFP.

UN spokesman Stephane Dujarric, pressed by reporters, refused to say whether Iran would or should be invited to the talks, which are to be held next month in Geneva.

“It is important that all those who have an influence on the current conflict be included in discussions but as to the exact list of those who will be invited to this new effort it has not yet been decided,” he was quoted as having said.

Dujarric described the talks as a series of “rolling meetings and discussions in Geneva and elsewhere” with no pre-set agenda.

Another UN official said earlier in Geneva that the UN envoy wanted to hold separate consultations with each of the parties to the conflict.

“Mr. De Mistura will have a broad series of discussions at various levels to harvest ideas and some common ground on how we can move forward based on the communiqué agreed in Geneva,” Ahmad Fawzi told reporters.

De Mistura is expected to brief the UN Security Council on the situation April 24 at a time when the conflict is at an impasse four years into a war that has left an estimated 200,000 dead.

In January, the UN envoy concluded that time was not right for another international conference on Syria, following the failure of a second round of peace talks in Geneva in February.

De Mistura has been trying to mediate between the fighting sides and recently said that the Syrian regime is willing to suspend its aerial bombardment of Aleppo for six weeks to allow for a localized humanitarian ceasefire, part of his efforts to end the nearly four-year war in the country.

The rebels in Aleppo later rejected the proposal, likely due to de Mistura’s earlier comments in which he said Assad was as “part of the solution” to the conflict in Syria.