To clarify the specific "report", I looked it up for you in Hebrew and tracked it back from there.
The story seems to have started in Iranian official media. [See: http://www.israellycool.com/2011/03/03/something-else-to-blame-on-the-jooooos/#idc-container ]
The claim in Maan Arabic News was attributed to unnamed "Egyptian sources". Interestingly, when Egypt recently blamed the Jews for sending sharks to Sharm, Arabic papers at least named the Egyptian government minister who thought up the claim. However, for the mercenary story, AlJazeera cited NO source. (On the contrary, they mentioned that an Israeli denies the story.)
Note that Maariv reported that Al Jazeera suddenly REMOVED its initial story!
http://www.the7eye.org.il/PaperReview/Pages/070311_Both_sides_claim_victory.aspx
I'd take that as a retraction for the moment.
"Inyan Merkazi" --the site that publicized in Hebrew the alleged Egyptian claims-- is not much of a newspaper. (I'm Israeli, and I don't recall ever hearing of the site till now.) It seems to have a lot of reposted stories from the Israeli Ynet online paper.
A pertinent question to explore is: Why black African migrant workers are paying the price for the real or perceived use of mercenaries in Libya http://www.theglobeandmail.com/news/world/africa-mideast/why-black-africans-are-paying-the-price-for-the-real-or-perceived-use-of-mercenaries-in-libya/article1933381/ The article provides perspective on whether many mercenaries are involved in the Libyan regime or whether allied tribes that support Kaddafi are falsely being labelled as "mercenaries".
Meanwhile, over at Al-Sharq Al-Awsat, Libyan rebels stated that SYRIAN pilots are flying Kaddafi's warplanes.
All considered, the accusation that Israelis are behind Kaddafi's paid African fighters is (ahem) dubious at best.