diff --git a/phpbb/config/default/container/services_mention.yml b/phpbb/config/default/container/services_mention.yml
index e1e8fa9a35..bae6b45bfe 100644
--- a/phpbb/config/default/container/services_mention.yml
+++ b/phpbb/config/default/container/services_mention.yml
@@ -30,3 +30,12 @@ services:
             - '@dbal.conn'
         tags:
             - { name: mention.source }
+
+    phpbb.mention.source.usergroup:
+        class: phpbb\mention\source\usergroup
+        arguments:
+            - '@dbal.conn'
+            - '@group_helper'
+            - '@user'
+        tags:
+            - { name: mention.source }
diff --git a/phpbb/phpbb/mention/controller/mention.php b/phpbb/phpbb/mention/controller/mention.php
index 14ec892269..8d731ae210 100644
--- a/phpbb/phpbb/mention/controller/mention.php
+++ b/phpbb/phpbb/mention/controller/mention.php
@@ -43,10 +43,10 @@ class mention
 
 	public function handle()
 	{
-		if (!$this->request->is_ajax())
-		{
-			redirect(append_sid($this->phpbb_root_path . 'index.' . $this->php_ext));
-		}
+//		if (!$this->request->is_ajax())
+//		{
+//			redirect(append_sid($this->phpbb_root_path . 'index.' . $this->php_ext));
+//		}
 
 		$keyword = $this->request->variable('keyword', '', true);
 		$topic_id = $this->request->variable('topic_id', 0);
diff --git a/phpbb/phpbb/mention/source/friend.php b/phpbb/phpbb/mention/source/friend.php
index 8f78159b6c..bb3ba9ecb7 100644
--- a/phpbb/phpbb/mention/source/friend.php
+++ b/phpbb/phpbb/mention/source/friend.php
@@ -15,9 +15,6 @@ namespace phpbb\mention\source;
 
 class friend extends user
 {
-	/** @var \phpbb\db\driver\driver_interface */
-	protected $db;
-
 	/** @var  \phpbb\user */
 	protected $user;
 
@@ -26,7 +23,6 @@ class friend extends user
 	 */
 	public function __construct(\phpbb\db\driver\driver_interface $db, \phpbb\user $user)
 	{
-		$this->db = $db;
 		$this->user = $user;
 
 		parent::__construct($db);
diff --git a/phpbb/phpbb/mention/source/group.php b/phpbb/phpbb/mention/source/group.php
new file mode 100644
index 0000000000..b503ac714c
--- /dev/null
+++ b/phpbb/phpbb/mention/source/group.php
@@ -0,0 +1,103 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license       GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\mention\source;
+
+abstract class group implements source_interface
+{
+	/** @var \phpbb\db\driver\driver_interface */
+	protected $db;
+
+	/** @var \phpbb\group\helper */
+	protected $helper;
+
+	/**
+	 * Constructor
+	 */
+	public function __construct(\phpbb\db\driver\driver_interface $db, \phpbb\group\helper $helper)
+	{
+		$this->db = $db;
+		$this->helper = $helper;
+	}
+
+	/**
+	 * Returns data for all board groups
+	 *
+	 * @return array Array of groups' data
+	 */
+	protected function get_groups()
+	{
+		static $groups = null;
+
+		if (is_null($groups))
+		{
+			$query = $this->db->sql_build_query('SELECT', [
+				'SELECT' => 'g.*',
+				'FROM'   => [
+					GROUPS_TABLE => 'g',
+				],
+			]);
+			$res = $this->db->sql_query($query);
+
+			$groups = [];
+			while ($row = $this->db->sql_fetchrow($res))
+			{
+				$group_name = $this->helper->get_name($row['group_name']);
+				$groups['names'][$row['group_id']] = $group_name;
+				$groups[$row['group_id']] = $row;
+				$groups[$row['group_id']]['group_name'] = $group_name;
+			}
+		}
+		return $groups;
+	}
+
+	/**
+	 * Builds a query for getting group IDs based on user input
+	 *
+	 * @param string $keyword  Search string
+	 * @param int    $topic_id Current topic ID
+	 * @return string Query ready for execution
+	 */
+	abstract protected function query($keyword, $topic_id);
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function get($keyword, $topic_id)
+	{
+		// Grab all group IDs
+		$res = $this->db->sql_query($this->query($keyword, $topic_id));
+
+		$group_ids = [];
+		while ($row = $this->db->sql_fetchrow($res))
+		{
+			$group_ids[] = $row['group_id'];
+		}
+
+		// Grab group data
+		$groups = $this->get_groups();
+
+		$matches = preg_grep('/^' . $keyword . '.*/i', $groups['names']);
+		$group_ids = array_intersect($group_ids, array_flip($matches));
+
+		$names = [];
+		foreach ($group_ids as $group_id)
+		{
+			$names['g' . $group_id] = [
+				'name' => $groups[$group_id]['group_name'],
+			];
+		}
+
+		return $names;
+	}
+}
diff --git a/phpbb/phpbb/mention/source/user.php b/phpbb/phpbb/mention/source/user.php
index be0d39f3af..55f94e4866 100644
--- a/phpbb/phpbb/mention/source/user.php
+++ b/phpbb/phpbb/mention/source/user.php
@@ -46,7 +46,9 @@ abstract class user implements source_interface
 		$names = [];
 		while ($row = $this->db->sql_fetchrow($res))
 		{
-			$names['u' . $row['user_id']] = $row['username'];
+			$names['u' . $row['user_id']] = [
+				'name' => $row['username'],
+			];
 		}
 
 		return $names;
diff --git a/phpbb/phpbb/mention/source/usergroup.php b/phpbb/phpbb/mention/source/usergroup.php
new file mode 100644
index 0000000000..1a0e20eff8
--- /dev/null
+++ b/phpbb/phpbb/mention/source/usergroup.php
@@ -0,0 +1,51 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license       GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\mention\source;
+
+class usergroup extends group
+{
+	/** @var  \phpbb\user */
+	protected $user;
+
+	/**
+	 * Constructor
+	 */
+	public function __construct(\phpbb\db\driver\driver_interface $db, \phpbb\group\helper $helper, \phpbb\user $user)
+	{
+		$this->user = $user;
+
+		parent::__construct($db, $helper);
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	protected function query($keyword, $topic_id)
+	{
+		$query = $this->db->sql_build_query('SELECT', [
+			'SELECT'    => 'g.group_id',
+			'FROM'      => [
+				GROUPS_TABLE => 'g',
+			],
+			'LEFT_JOIN' => [
+				[
+					'FROM' => [USER_GROUP_TABLE => 'ug'],
+					'ON'   => 'g.group_id = ug.group_id'
+				]
+			],
+			'WHERE'     => 'ug.user_id = ' . (int) $this->user->data['user_id'],
+		]);
+		return $query;
+	}
+}