United Nations Syria envoy Staffan De Mistura has invited the Syrian government and opposition groups for separate peace talks in Geneva next month, but no terror groups— such as the Islamic State—will be represented, a U.N. spokesman said Friday.  

De Mistura has set plans for “low key” negotiations with representatives of Syrian President Bashar al-Assad’s government and some opposition groups over a four to six-week period, in hopes of ending the four-year civil war that has killed more than 220,000 people.

"There will be no big meeting at the end. There will be no fanfare at the conclusion," U.N. spokesman Ahmad Fawzi said at a briefing Friday.

Fawzi told reporters major powers and regional players were asked to participate in the talks, but an invitation has not been extended to members of the Islamic State (ISIS) or the Jabhat al-Nusra group, which are classified as "terrorist organizations,” Reuters reported.

Some of the parties present at the talks would be able to communicate with the terror groups, Fawzi added.

A spokesman for de Mistura later said Iran is among the parties invited to attend the new series of peace talks that will start in early May in Geneva. Iran has not responded, Michael Contet said in an email.

ISIS - an Al Qaeda offshoot -- has seized large parts of Syria and neighboring Iraq, intensifying a bloody war between Syrian government forces and other opposition groups that has killed 220,000 and displaced nearly four million, according to U.N. reports.

Iran is among those invited to Switzerland, Fawzi told Reuters.

Separate talks between several world powers and Iran on Iran's nuclear program may be settled by the end of June. A breakthrough on nuclear negotiations would ease tensions between Tehran and Washington, two of the leading powers for and against Assad. That could create diplomatic momentum to help talks on Syria’s future.

Fawzi said De Mistura hoped to report back to U.N. Secretary-General Ban Ki-moon on the Syria talks by June 30.

The Associated Press contributed to this report.