Product categories and subcategories

[malo6]

Hello,
On product page I want to display all categories and subcategories to which the product is assigned. Something like this:
-Category 1
--Sub1
--Sub2
-Category 2
--Sub3
--Sub4

My current code is:
 

					{foreach from=$product_categories item=product_category}
						{if $product_category.id_category != 2}
							<li >
								<a href="{$link->getCategoryLink($product_category.id_category, $product_category.link_rewrite)}"
								title="{$product_category.name}">{$product_category.name}</a>
							</li>	
						{/if}
					{/foreach}

But its print all categories in every line without category tree.