Pirates have been moving further out to sea to evade patrols
Somali pirates have hijacked a 20,000-tonne German container ship in the Indian Ocean, a merchant mariners' charity reports.
They seized the ship on Saturday about 400 nautical miles (740km) off the southern Somali port of Kismayo, between the Seychelles and Kenya.
A crew of 24 is believed to be aboard the ship, the Kenya-based East African Seafarers' Assistance Programme said.
The names of the ship and identities of the crew members are being verified.
Germany's foreign ministry said it was seeking "concrete evidence" that a German-flagged vessel had been captured.
"The federal government is dealing with the case and all the appropriate public authorities are participating intensively," an unnamed spokeswoman told Reuters news agency.
Somalia-based pirates have captured dozens of ships over the past year.
They have expanded their reach far out into the Indian Ocean since foreign warships started patrolling coastal areas.
"We believe the German ship has 24 crew on board," said Andrew Mwangura of the Mombasa-based East African Seafarers' Assistance Programme.
"We're trying to establish their identities and the name of the vessel," he told Reuters.
'Saved by barbed wire'
Pirates say the presence of high-tech foreign warships in coastal waters has made their operations more dangerous.
One pirate in the northern port of Bosasso, who asked not to be named, told Reuters he had been part of an aborted attack on another large commercial vessel late on Saturday.
"We opened fire on a ship near the Gulf of Aden but our ladder was too short to climb up," he said.
"It escaped at high speed. We were nine pirates in two speed boats and immediately we came back. We feared attacks by the warships."
An Israeli cargo ship came under fire from pirates en route to Kenya on Saturday but was apparently saved by coils of barbed wire hung around the hull to repel boarders.
Rafi Danieli, managing director of the Zim shipping line, said company headquarters had received a message from the captain of the ship on Saturday morning saying that pirates in speedboats were firing at him and attempting to take over the ship.
The pirates continued to trail the ship, the Africa Star, but finally gave up, reportedly after the appearance of a plane sent out by the British Pirate Reporting Centre, which is in the area.
No Israelis were aboard the vessel, the company said.