The European Union is ready to defend commercial vessels from Somali pirates once NATO's mission expires later this month, DPA quoted EU foreign policy chief Javier Solana as saying Wednesday. "We have a responsibility to escort, deter and protect, and it will be done with very robust rules of engagement," Solana said ahead of a meeting of NATO foreign ministers at the alliance's headquarters in Brussels. The EU's naval force for Somalia "Atalanta" mission, which consists of six warships and three maritime reconnaissance aircraft, is due to start escorting merchant ships and World Food Programme vessels delivering food aid to Africa on Monday. It takes over from NATO's own flotilla, which has been patrolling the Somali coast since late October. On Tuesday, the United Nations' Security Council gave its formal green-light to the EU mission, which is to last for one year at a cost of 8.3 million euros (10.5 million dollars). German Foreign Minister Frank-Walter Steinmeier stressed Wednesday the necessity of ensuring that vessels are protected by international forces. "The (naval) presence on the African coast has already saved a few ships from being hijacked over the past few days," Steinmeier said upon his arrival in Brussels. Solana conceded Wednesday that there were still a number of legal issues that needed to be resolved. One concerns the different rules which EU member states apply on the detention of pirates. "We need to coordinate that, but every country has a position - and that position is that they will not allow pirates to play around," Solana said. NATO Secretary General Jaap de Hoop Scheffer has welcomed the EU mission, saying it should be seen as "complementary" to NATO's force of four warships. Speaking Tuesday, de Hoop Scheffer said five hijacking attempts, including of a cruise liner, had reportedly taken place over the last 24 hours, all of them "adequately treated by NATO." NATO commanders have stressed the need for the alliance to enforce maritime security in a more permanent way. But officials note that any decision will likely require months of discussions. "NATO is indeed studying a longer-term role ... but there's a lot of water on this globe, and this issue will be on the agenda for some time to come," the NATO chief said. According to the International Maritime Bureau (IMB), there have been almost 100 attempts at piracy in the region this year, with around 40 of them successful.