They may not be officially part of the Russian intelligence apparatus but they definitely don't seem to act contrary to Russian interests, they actively ignored leaks about the Russian government[4], and their public tweets about the Panama Papers were a lot more consistent with protecting Russian interests rather than the purported belief in exposing secrets[5]. They also didn't ask whether they were being used by sources like Guccifer 2 which was later revealed to be a Russian front.
Other governments have come to the same conclusion – e.g. here's a German report which alleges British and French agreement:
http://www.focus.de/politik/ausland/merkel-vorgefuehrt-russi...
1. http://www.slate.com/blogs/the_slatest/2016/07/25/what_wikil...
2. http://nymag.com/selectall/2016/07/why-did-wikileaks-help-do...
3. https://apnews.com/b70da83fd111496dbdf015acbb7987fb/private-...
4. http://foreignpolicy.com/2017/08/17/wikileaks-turned-down-le...
5. https://mobile.twitter.com/wikileaks/status/7174580643249643... and https://mobile.twitter.com/wikileaks/status/7176700566505308...