NEW DELHI - The Indian navy captured 23 pirates who threatened a merchant vessel Saturday in the lawless waters of the Gulf of Aden, where dozens of ships have come under attack by gunmen in recent months.

An Indian navy ship, the INS Mysore, was escorting merchant ships in the region near Somalia when it received a distress call from seamen on board the MV Gibe, who said they were being attacked by two boats.

The distress call said the pirates were firing as their boats closed in on the Gibe, according to a statement from the Indian government. The pirate boats attempted to escape when they saw the Mysore and its helicopter, but were boarded by Indian marine commandoes, the statement said.

The pirates had "a substantial cache of arms and equipment," including seven AK-47 assault rifles, three machine-guns, a rocket-propelled grenade launcher and other weapons, the statement said. They also found a GPS receiver and other equipment.

The pirates were from Somalia and Yemen, two countries on the coast of the Gulf of Aden.

The Gibe was flying an Ethiopian flag, the statement said, but there was no further information about the ship.

Last month, India's navy drew criticism after sinking a Thai fishing trawler that had been commandeered hours earlier by pirates. At least one Thai crew member was killed in the attack, which the Indian navy had originally announced by saying it had sunk a pirate "mother ship." The Indian navy defended its actions, saying it had fired in self-defence.

Somali pirates have become increasingly brazen, and recently seized a Saudi supertanker loaded with $100 million of crude oil. Many of the vessels are taken to pirate-controlled regions in Somalia, where they are held for ransom.

It was not immediately clear what would happen to the pirates captured by the Indians, or where they would be taken. The statement said only that the prisoners and their weapons would be "handed over to appropriate authorities ashore."

Most foreign navies patrolling the Somali coast have been reluctant to detain suspects because of uncertainties over where they would face trial, since Somalia has no effective central government or legal system.

An estimated 1,500 pirates are based in Somalia's semiautonomous Puntland region, raking in millions of dollars.

U.S. Secretary of State Condoleezza Rice will present a draft Security Council resolution next week asking the United Nations to authorize "all necessary measures" against piracy from Somalia.

But on Friday, the commander of the U.S. navy's 5th Fleet expressed doubt about the wisdom of launching attacks against Somali pirates on land, as the draft proposes.

U.S. Vice-Admiral Bill Gortney told reporters that it is difficult to identify pirates, and the potential for killing innocent civilians "cannot be overestimated."