NAIROBI, Oct. 5 (Xinhua) -- Somali pirates have released a Turkish vessel which was captured in July with 23 crew members aboard, a regional maritime official confirmed on Monday.

Andrew Mwangura, the East Africa Coordinator of Seafarers Assistance Program, said the Istanbul-based cargo ship the MV Horizon-1 was set free by the pirates on Monday.

The vessel was hijacked in July in the Gulf of Aden.

The development came after pirates in the Horn of Africa country have hijacked a Spanish fishing boat in the dangerous waters of the Indian Ocean after a month of a lull of activity along the coast of the Horn of Africa nation, Mwangura confirmed on Friday.

The official said the 100-meter MS Alakrana was seized early Friday by armed gunmen with 36 crew members on board.

Piracy has become rampant off the coast of Africa, especially in the waters near Somalia, which has been without an effective government since 1991.

Ransoms started out in the tens of thousands of dollars and have since climbed into the millions.

An estimated 25,000 ships annually cruise the Gulf of Aden, off Somalia's northern coast. Over 10 ships and 200 crew members are still held by Somali pirates.

The Gulf of Aden, off the northern coast of Somalia, has the highest risk of piracy in the world. About 25,000 ships use the channel south of Yemen, between the Red Sea and the Arabian Sea.