The two-day meeting, a followup to earlier talks, will gather "all the countries that are involved" in the United States-led fight against ISIL, including Persian Gulf nations, one of the sources said.
"I think it'll be sort of a general appraisal of where we're at, what needs to be done," added the source, who asked for anonymity.
Another diplomatic source said the meeting is "more an exchange of information" and a chance for co-ordination, rather than a forum for major decisions, AFP reported.
The talks among defence chiefs and their deputies coincide with the rise of ISIL in Libya, which has heightened concerns in the region after the group seized parts of Iraq and Syria last year.