Tanzania has arrested five suspected Somali pirates on an island close to its natural gas reserves in the southern part of the east African country, said the army.
Tanzania's coastline is fast becoming a major gas hub with major discoveries made there.

"The Tanzanian navy arrested the pirates in their skiff on April 18 near the Songsongo gas fields. Each of the five pirates was found in possession of a sub-machine gun," Tanzanian army spokesman Kapambale Mgawe said, Reuters reports.

"The pirates arrested in Tanzania were in close communication with a mother ship that has seven more pirates. A Spanish vessel has managed to arrest the pirates on this mother ship and they are being brought to Tanzania today for custody."

Mgawe said the mother ship used by the pirates was formerly a Sri Lankan fishing vessel with six crew members on board.

"The Tanzanian navy has been conducting regular patrols to ensure Somali pirates do not enter our territorial waters from deep seas to carry out attacks," he said.

Last October, Tanzania arrested seven suspected Somali pirates following an attack on an oil and gas exploration ship operated by Brazilian petroleum company Petrobras off the coast of the country.

And last year, it ordered its army to escort ships searching for oil and gas off its coast to protect them from pirates, who are believed to be targeting expatriate workers on exploration ships.

East Africa's second-biggest economy has licensed at least 18 international companies to look for offshore and onshore energy reserves.

The arrest of the five suspects brings to 23 the total number of pirates arrested in Tanzania following attacks in its Indian Ocean territorial waters in the past few years.