The editorial was published amid renewed fighting in eastern Democratic Republic of Congo between the government and troops rebelling against the government, the Comitee to Protect Journalists (CPJ) said Thursday night.
News accounts had reported on a leaked United Nations report that blamed neighboring Rwanda for supplying military assistance to the rebels.
Mende also accused Le Journal of stigmatizing an entire community with the editorial, called "Insecurity in Eastern Democratic Republic of Congo: These Congolese in the Tutsi Spider's Web," a reference to ethnic Tutsi dominating the Rwandan government.
The editorial, a copy of which was obtained by CPJ, accused Congolese of Rwandan ancestry or "Rwandophones," of secretly aiding and abetting the interests of Rwanda in DRC.
Le Journal Editor Patrice Booto rejected the accusations, he told CPJ.
The newspaper has not published since the suspension.
Earlier in June, Mende accused Rwanda of providing training, recruits. and weapons to rebels in eastern DRC.
The Rwandan government strongly denied the accusations, saying Congo should shoulder the burden of its internal problems and stop attributing them to Kigali.Media reports recently indicated that Tutsis in Eastern Congo had been targeted, killed and their homes burnt by militia groups.