diff --git a/app/models/user.rb b/app/models/user.rb
index a3d2449d2..af65d5aaa 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -887,6 +887,10 @@ class User < Principal
     project_ids.map(&:to_i)
   end
 
+  def self.prune(age=1.day)
+    User.where("created_on < ? AND status = ?", Time.now - age, STATUS_REGISTERED).destroy_all
+  end
+
   protected
 
   def validate_password_length
diff --git a/lib/tasks/redmine.rake b/lib/tasks/redmine.rake
index 2bebaf18c..8cdf6f80f 100644
--- a/lib/tasks/redmine.rake
+++ b/lib/tasks/redmine.rake
@@ -40,6 +40,13 @@ namespace :redmine do
     end
   end
 
+  namespace :users do
+    desc 'Remove users who could not be activated after one day.'
+    task :prune => :environment do
+      User.prune
+    end
+  end
+
   namespace :watchers do
     desc 'Removes watchers from what they can no longer view.'
     task :prune => :environment do
diff --git a/test/unit/user_test.rb b/test/unit/user_test.rb
index ab1fe56ab..63867b92f 100644
--- a/test/unit/user_test.rb
+++ b/test/unit/user_test.rb
@@ -1313,6 +1313,16 @@ class UserTest < ActiveSupport::TestCase
     assert_equal [], User.find(2).bookmarked_project_ids
   end
 
+  def test_prune_should_destroy_not_activated_old_users
+    User.generate!(:status => User::STATUS_REGISTERED, :created_on => 2.days.ago)
+    User.generate!(:status => User::STATUS_REGISTERED, :created_on => 2.days.ago)
+    User.generate!(:status => User::STATUS_REGISTERED)
+
+    assert_difference 'User.count', -2 do
+      User.prune
+    end
+  end
+
   if Object.const_defined?(:OpenID)
     def test_setting_identity_url
       normalized_open_id_url = 'http://example.com/'