Kenya has borne the brunt of taking in and prosecuting sea bandits seized by foreign navies patrolling the Gulf of Aden's busy shipping lanes that link Europe with Africa and Asia.
"Parliament has already approved amendments to the penal code to ensure that Somali pirates can now be prosecuted in Tanzania," Tanzania's Attorney General Frederick Werema told Reuters.
Pirates continue to outwit an international flotilla of warships, forcing some shipping companies to re-route around southern Africa while others employ private armed guards.
Often pirates arrested on the high seas are returned to Somalia's lawless shores because of disagreements over who should prosecute them.
Catherine Ashton, the EU's special representative for foreign affairs and security policy, said piracy posed a regional security threat and needed an international response.
"Piracy is one of the big challenges of our times both for the region and for the international community. It undermines maritime security in the Indian Ocean and stability and development in the region," she told reporters in Tanzania's commercial capital Dar es Salaam.
The seas off Somalia are among the world's most dangerous for merchant shipping. The number of attacks worldwide jumped by 40 percent last year, with gunmen from the failed Horn of Africa state accounting for more than half the 406 reported incidents.
Ashton is on a three-nation tour of Kenya, Tanzania and Seychelles to bolster the region's response to piracy and pledge an increased international commitment.
She said the EU would help Tanzania develop the necessary infrastructure to detain pirates and put them on trial.
On Wednesday, Kenya's foreign minister, Moses Wetangula, said his government would cease prosecuting pirates in four months if cost and security guarantees were not forthcoming.
Earlier, the British High Commission in Tanzania said one its warships, Chatham, had destroyed two suspected pirate boats off the coast of Tanzania last week.
Commander Simon Huntington said Royal Marines disarmed 10 suspected pirates inside Tanzania's exclusive economic zone before releasing them.
