diff --git a/src/Composer/Command/DebugPackagesCommand.php b/src/Composer/Command/DebugPackagesCommand.php
new file mode 100644
index 000000000..b92d06373
--- /dev/null
+++ b/src/Composer/Command/DebugPackagesCommand.php
@@ -0,0 +1,62 @@
+<?php
+
+/*
+ * This file is part of Composer.
+ *
+ * (c) Nils Adermann <naderman@naderman.de>
+ *     Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Composer\Command;
+
+use Composer\Autoload\AutoloadGenerator;
+use Composer\DependencyResolver;
+use Composer\DependencyResolver\Pool;
+use Composer\DependencyResolver\Request;
+use Composer\DependencyResolver\Operation;
+use Composer\Package\LinkConstraint\VersionConstraint;
+use Composer\Repository\PlatformRepository;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * @author Jordi Boggiano <j.boggiano@seld.be>
+ */
+class DebugPackagesCommand extends Command
+{
+    protected function configure()
+    {
+        $this
+            ->setName('debug:packages')
+            ->setDescription('Lists all existing packages and their version')
+            ->setHelp(<<<EOT
+<info>php composer debug:packages</info>
+
+EOT
+            )
+        ;
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output)
+    {
+        $composer = $this->getComposer();
+
+        // create local repo, this contains all packages that are installed in the local project
+        $localRepo           = $composer->getRepositoryManager()->getLocalRepository();
+        // create installed repo, this contains all local packages + platform packages (php & extensions)
+        $installedRepo       = new PlatformRepository($localRepo);
+
+        foreach ($installedRepo->getPackages() as $package) {
+            $output->writeln('installed: '.$package->getName().' '.$package->getVersion());
+        }
+
+        foreach ($composer->getRepositoryManager()->getRepositories() as $repository) {
+            foreach ($repository->getPackages() as $package) {
+                $output->writeln('available: '.$package->getName().' '.$package->getVersion());
+            }
+        }
+    }
+}
diff --git a/src/Composer/Console/Application.php b/src/Composer/Console/Application.php
index 5730add3e..1f0f12e8a 100644
--- a/src/Composer/Console/Application.php
+++ b/src/Composer/Console/Application.php
@@ -16,7 +16,7 @@ use Symfony\Component\Console\Application as BaseApplication;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Finder\Finder;
-use Composer\Command\InstallCommand;
+use Composer\Command;
 use Composer\Composer;
 
 /**
@@ -63,6 +63,7 @@ class Application extends BaseApplication
      */
     protected function registerCommands()
     {
-        $this->add(new InstallCommand());
+        $this->add(new Command\InstallCommand());
+        $this->add(new Command\DebugPackagesCommand());
     }
 }