De acordo com Portal da Imigração da UE :
If you hold a residence permit or a long-stay visa issued by a Schengen area country, you will have the same freedom of travel as a Schengen short-stay visa holder. If you have a Schengen visa and wish to visit any of the six EU countries which are outside the Schengen area (Bulgaria, Romania, Croatia, Cyprus, Ireland, the United Kingdom), you normally need to apply for a separate national visa for each country. However, holders of Schengen visas valid for multiple entries can enter Bulgaria, Croatia, Cyprus and Romania without an additional national visa.