diff --git a/mod/assign/externallib.php b/mod/assign/externallib.php
index fa2b761c36a..7e54b4fb8cd 100644
--- a/mod/assign/externallib.php
+++ b/mod/assign/externallib.php
@@ -2636,6 +2636,7 @@ class mod_assign_external extends \mod_assign\external\external_api {
         global $DB, $CFG;
         require_once($CFG->dirroot . "/mod/assign/locallib.php");
         require_once($CFG->dirroot . "/user/lib.php");
+        require_once($CFG->libdir . '/grouplib.php');
 
         $params = self::validate_parameters(self::list_participants_parameters(),
                                             array(
@@ -2657,8 +2658,10 @@ class mod_assign_external extends \mod_assign\external\external_api {
         $assign->require_view_grades();
 
         $participants = array();
+        $coursegroups = [];
         if (groups_group_visible($params['groupid'], $course, $cm)) {
             $participants = $assign->list_participants_with_filter_status_and_group($params['groupid'], $params['tablesort']);
+            $coursegroups = groups_get_all_groups($course->id);
         }
 
         $userfields = user_get_default_fields();
@@ -2709,9 +2712,12 @@ class mod_assign_external extends \mod_assign\external\external_api {
                 $userdetails['submissionstatus'] = $record->submissionstatus;
                 if (!empty($record->groupid)) {
                     $userdetails['groupid'] = $record->groupid;
-                }
-                if (!empty($record->groupname)) {
-                    $userdetails['groupname'] = $record->groupname;
+
+                    if (!empty($coursegroups[$record->groupid])) {
+                        // Format properly the group name.
+                        $group = $coursegroups[$record->groupid];
+                        $userdetails['groupname'] = format_string($group->name);
+                    }
                 }
                 // Unique id is required for blind marking.
                 $userdetails['recordid'] = -1;
@@ -2826,6 +2832,7 @@ class mod_assign_external extends \mod_assign\external\external_api {
         global $DB, $CFG;
         require_once($CFG->dirroot . "/mod/assign/locallib.php");
         require_once($CFG->dirroot . "/user/lib.php");
+        require_once($CFG->libdir . '/grouplib.php');
 
         $params = self::validate_parameters(self::get_participant_parameters(), array(
             'assignid' => $assignid,
@@ -2868,9 +2875,11 @@ class mod_assign_external extends \mod_assign\external\external_api {
 
         if (!empty($participant->groupid)) {
             $return['groupid'] = $participant->groupid;
-        }
-        if (!empty($participant->groupname)) {
-            $return['groupname'] = $participant->groupname;
+
+            if ($group = groups_get_group($participant->groupid)) {
+                // Format properly the group name.
+                $return['groupname'] = format_string($group->name);
+            }
         }
 
         // Skip the expensive lookup of user detail if we're blind marking or the caller
diff --git a/mod/assign/tests/externallib_test.php b/mod/assign/tests/externallib_test.php
index fa4a3ebce31..75095906e79 100644
--- a/mod/assign/tests/externallib_test.php
+++ b/mod/assign/tests/externallib_test.php
@@ -2854,6 +2854,54 @@ class externallib_test extends \mod_assign\externallib_advanced_testcase {
         }
     }
 
+    /**
+     * Test for WS returning group.
+     * @covers ::get_participant
+     * @covers ::list_participants
+     */
+    public function test_participants_info_with_groups() {
+        global $CFG;
+        $this->resetAfterTest(true);
+        $CFG->showuseridentity = 'idnumber,email,phone1,phone2,department,institution';
+
+        // Set up filtering.
+        filter_set_global_state('multilang', TEXTFILTER_ON);
+        filter_set_applies_to_strings('multilang', true);
+        \external_settings::get_instance()->set_filter(true);
+
+        $result = $this->create_assign_with_student_and_teacher([
+            'assignsubmission_onlinetext_enabled' => 1,
+            'teamsubmission' => 1
+        ]);
+        $assignmodule = $result['assign'];
+        $student = $result['student'];
+        $teacher = $result['teacher'];
+        $course = $result['course'];
+        $context = \context_course::instance($course->id);
+
+        $gname = '<span class="multilang" lang="en">G (en)</span><span class="multilang" lang="es">G (es)</span>';
+        $group = $this->getDataGenerator()->create_group(['courseid' => $course->id, 'name' => $gname]);
+        groups_add_member($group, $student);
+
+        $cm = get_coursemodule_from_instance('assign', $assignmodule->id);
+        new mod_assign_testable_assign($context, $cm, $course);
+
+        // Prepare submission.
+        $this->setUser($teacher);
+
+        // Test mod_assign_external::list_participants.
+        $participants = \mod_assign_external::list_participants($assignmodule->id, $group->id, '', 0, 0, false, true, true);
+        $participants = \external_api::clean_returnvalue(mod_assign_external::list_participants_returns(), $participants);
+        $this->assertEquals($group->id, $participants[0]['groupid']);
+        $this->assertEquals(format_string($gname, true), $participants[0]['groupname']);
+
+        // Test mod_assign_external::get_participant.
+        $participant = mod_assign_external::get_participant($assignmodule->id, $student->id, true);
+        $participant = \external_api::clean_returnvalue(mod_assign_external::get_participant_returns(), $participant);
+        $this->assertEquals($group->id, $participant['groupid']);
+        $this->assertEquals(format_string($gname, true), $participant['groupname']);
+    }
+
     /**
      * Test test_view_assign
      */