Updated

U.S. warships fired on Somali pirates trying to resupply colleagues who hijacked a Danish-owned tug boat, a district commissioner said Monday.

"Some of the artillery shells hit around the coastline but no human casualties were reported. Unfortunately the gangs escaped," Abdullahi Said, the district commissioner for Eyl, told the AP by phone.

The hijacked ship, which has six crew members onboard, is stationed around 40 kilometers (25 miles) east of Eyl, he said. The coastal town is some 900 kilometers (560 miles) north of the capital, Mogadishu.

All crew members on the Svitzer Korsakov — a British captain, an Irish engineer and four Russian crew — were believed to be unharmed.

A spokeswoman for the U.S. Fifth Fleet in Bahrain, which oversees operations off the pirate-infested Somali coast, said she had not heard about the incident.

But Denise Garcia said the U.S. Navy had been monitoring the ship since Feb. 4, three days after it was hijacked off the coast of Puntland, a semiautonomous region of northeast Somalia. She said U.S. warships had communicated with the pirates by radio and "encouraged them to leave the ship and let it go."

The U.S. Navy has led international patrols to try to combat piracy in the region. In one incident last year, the guided missile destroyer USS Porter opened fire to destroy pirate skiffs tied to a Japanese tanker.

Piracy is increasingly common along Somalia's 3,000-kilometer (1,880-mile) coast, which is the longest in Africa and near key shipping routes connecting the Red Sea with the Indian Ocean.

Pirates seized more than two dozen ships off the Somali coast last year.

The International Maritime Bureau, which tracks piracy, said in its annual report earlier this year that global pirate attacks rose by 10 percent in 2007, marking the first increase in three years as sea robbers made a strong comeback.

Wracked by more than a decade of violence and anarchy, Somalia does not have its own navy and the transitional government formed in 2004 with U.N. help has struggled to assert control.