Security forces in central Somalia have apprehended a suspect in the hijacking of a humanitarian aid vessel at the town of Merka town four months ago.
There were some 35 piracy incidents last year in Somali waters
The man is alleged to be one of three people who hijacked a vessel chartered by the World Food Programme.
The waters off Somalia are the most dangerous in the world and ships have been warned to stay far out to sea.
Meanwhile, the UN has said Somali militias are looting food aid, hitting the drought relief effort.
The rise in piracy means that aid to the 2m people suffering the effects of drought is now delivered overland - where it is vulnerable to the roadblocks operated by gunmen.
UN Humanitarian Coordinator for Somalia Maxwell Gaylard urged community and political leaders to ensure that food aid could get through safely.
Somalia has had no central government for 15 years and rival warlords have divided the country between them.
The suspect in the WFP hijacking is being held in Merka's central prison, according to Nuriyeh Ali Farah, a senior figure in the militia which controls the region.
"More than two dozen security forces from the region surrounded the house in which [he] was hiding," he told the BBC.
"We got the information from our secret services which led us to the successful arrest."
The Somalis in Mombasa deny the charges of piracy
The MV Miltzow was held for three days last October.
Meanwhile, the trial of 10 alleged pirates arrested by the US navy has begun in the Kenyan port of Mombasa.
The trial in Mombasa follows last week's ruling that the court can hear the case, even though the alleged offences took place on the high seas.
The men have denied the charges and said they did not know why they had been "abducted" from their fishing boat.
But Indian sailors taken hostage by pirates have identified the men.
There are no widely recognised courts in Somalia, however, local warlords and Islamic groups have set up judicial systems in some areas.
US ambassador to Kenya William Bellamy said the rescued Indian vessel was brought to Mombasa because it was the nearest port.
"I believe under international law Kenya could if it chose take jurisdiction in this case. Other states, however, may wish to take jurisdiction," he said while on a visit to Mombasa last week.
Reuters news agency reports that a 3,000-ton cargo ship has been towed into the Seychelles port of Victoria, after being seized by pirates off Somalia.
The ship's captain, Deaa Naseh, said the gunmen had thrown their weapons into the sea after being approached by a US navy ship.
Shipping companies say there have been 35 incidents of piracy off the Indian Ocean coast of Somalia in the past nine months.
The transitional Somali government has signed a $50m (£28m) two-year deal with a private US marine security company to carry out coastal patrols.
However, it is not clear where this money would come from, as the government has not effectively taken office. The security company has not started work.