diff --git a/src/app/pages/observations/observation-detail.component.html b/src/app/pages/observations/observation-detail.component.html
index 59e49491..b5e58fff 100644
--- a/src/app/pages/observations/observation-detail.component.html
+++ b/src/app/pages/observations/observation-detail.component.html
@@ -27,7 +27,7 @@
   </otp-operator-detail>
 </otp-modal>
 
-<form *ngIf="!loading" name="form" class="c-form" (ngSubmit)="!isDisabled() && f.valid && onSubmitForReview()" #f="ngForm" novalidate>
+<form *ngIf="!loading" name="form" class="c-form" (ngSubmit)="!isDisabled() && !unknownOperatorSelected && f.valid && onSubmitForReview()" #f="ngForm" novalidate>
   <div class="c-container -j-between -t-d-column -t-a-start">
     <h2 *ngIf="isDisabled() && !isCopied">{{'Observation details' | translate}}</h2>
     <h2 *ngIf="(!isDisabled() && !observation) || isCopied">{{'New observation' | translate}}</h2>
@@ -196,7 +196,7 @@ <h3>{{'Upload report' | translate}}</h3>
     </div>
 
     <!-- 3. Operator -->
-    <div class="form-group -required" [ngClass]="{ 'has-error': f.submitted && !operator_id.valid }">
+    <div class="form-group -required" [ngClass]="{ 'has-error': f.submitted && (!operator_id.valid || unknownOperatorSelected) }">
       <label for="operator_id">{{'Operator' | translate}}</label>
       <ss-multiselect-dropdown
         [texts]="multiSelectTexts"
@@ -207,8 +207,10 @@ <h3>{{'Upload report' | translate}}</h3>
         name="operator_id"
         #operator_id="ngModel"
         [disabled]="isDisabled()"
+        required
       ></ss-multiselect-dropdown>
       <div *ngIf="f.submitted && !operator_id.valid" class="help-text">{{'Please select an operator' | translate}}</div>
+      <div *ngIf="unknownOperatorSelected" class="help-text">{{'You will not be able to submit this observation to review with unknown operator selected' | translate}}</div>
       <div class="note" *ngIf="!isDisabled()">
         <button type="button" class="c-button -primary" (click)="onClickAddOperator('operator')">{{'Add a new producer to the list' | translate}}</button>
       </div>
diff --git a/src/app/pages/observations/observation-detail.component.ts b/src/app/pages/observations/observation-detail.component.ts
index ba117eb2..1d278b35 100644
--- a/src/app/pages/observations/observation-detail.component.ts
+++ b/src/app/pages/observations/observation-detail.component.ts
@@ -67,6 +67,7 @@ export class ObservationDetailComponent implements OnDestroy {
   subcategories: Subcategory[] = [];
   severities: Severity[] = [];
   _operators: Operator[] = []; // Ordered by name, filtered by country
+  unknownOperator: Operator = null; // Special unknown operator
   governments: Government[] = [];
   observers: Observer[] = []; // Ordered by name
   fmus: Fmu[] = [];
@@ -349,9 +350,13 @@ export class ObservationDetailComponent implements OnDestroy {
 
   get operators() { return this._operators; }
   set operators(collection) {
-    this._operators = collection;
-    this.operatorsOptions = collection.map((o) => ({ id: o.id, name: o.name }));
-    this.relevantOperatorsOptions = this.operators.map((operator) => ({ id: operator.id, name: operator.name }));
+    if (this.unknownOperator) {
+      this._operators = [this.unknownOperator, ...collection];
+    } else {
+      this._operators = collection;
+    }
+    this.operatorsOptions = this._operators.map((o) => ({ id: o.id, name: o.name }));
+    this.relevantOperatorsOptions = collection.map((o) => ({ id: o.id, name: o.name }));
   }
 
   get operatorChoice() { return this.observation ? this.observation.operator : this._operatorChoice; }
@@ -387,6 +392,9 @@ export class ObservationDetailComponent implements OnDestroy {
       this.operatorsSelection = [];
     }
   }
+  get unknownOperatorSelected() {
+    return this.operatorChoice && this.unknownOperator && +this.operatorChoice.id === +this.unknownOperator.id;
+  }
 
   get fmu() { return this.observation ? this.observation.fmu : this._fmu; }
   set fmu(fmu) {
@@ -758,6 +766,12 @@ export class ObservationDetailComponent implements OnDestroy {
       this.updateTranslatedOptions(this.coordinatesFormats, 'coordinatesFormat');
     });
 
+    this.operatorsService.getAll({ filter: { slug: 'unknown' }}).then((operators) => {
+      if (operators.length > 0) {
+        this.unknownOperator = operators[0];
+      }
+    });
+
     this.observersService.getAll({ sort: 'name' })
       .then((observers) => {
         this.observers = observers;
diff --git a/src/assets/locale/zu.json b/src/assets/locale/zu.json
index 65a7fe7d..4c469cf4 100644
--- a/src/assets/locale/zu.json
+++ b/src/assets/locale/zu.json
@@ -396,5 +396,6 @@
   "Please pick sub-category first.": "Please pick sub-category first.",
   "Add a new government entity to the list": "Add a new government entity to the list",
   "Add a new producer to the list": "Add a new producer to the list",
-  "Please select an existing report or upload a new one": "Please select an existing report or upload a new one"
+  "Please select an existing report or upload a new one": "Please select an existing report or upload a new one",
+  "You will not be able to submit this observation to review with unknown operator selected": "You will not be able to submit this observation to review with unknown operator selected"
 }