<form action="<?php echo $formAction; ?>" method="post">
  <input type="text" name="user">
  <input type="password" name="pass">
  <input type="submit" value="<?php echo $btnMsg; ?>">
  <?php
    if(isset($_SESSION['activeCaptcha']) && $_SESSION['activeCaptcha']):
      require_once('recaptchalib.php');
      echo recaptcha_get_html("klucz_publiczny");
    endif;
  ?>
</form>