At least nine Somali pirates have been captured and another three killed after Yemeni special forces launched a raid on a hijacked tanker in the Gulf of Aden, a government official said.
The operation on Monday freed the Qana, which had been taken by the pirates off Yemen's coast a day earlier.
In total, at least five pirates have been killed by Yemeni navy commandos during their attempt over the last two days to take back the vessel, which was not carrying any cargo when it was seized.
The Yemeni navy is escorting the tanker, which has a 23-member crew, to the port of Aden on the southern tip of the Arabian Peninsula.
The pirates had briefly seized three other vessels earlier before Yemeni forces freed them, a Yemeni official said.
Yemen, one of the world's poorest countries, lies across the Gulf of Aden from Somalia and relies heavily on its exports of about 200,000 barrels of oil per day.
Pirates have taken millions of dollars in ransom payments by taking control of ships and holding crews hostage over the last year.
They have stepped up attacks on ships passing through the Gulf of Aden, an important route for ships carrying oil and cargo, since February.
Recent good weather has helped pirates stage their attacks on ships, even though foreign navies are running patrols off the Somali coast.
Pirates attacks almost doubled in the first quarter of 2009, with nearly all of them due to Somalia, the London-based International Maritime Bureau says.