BAGHDAD (AP) — Gunmen robbed four commercial ships anchored near the southern oil hub of Basra in a rare attack off the Iraqi coast, the US Navy said yesterday.

Two men armed with AK-47 rifles boarded the American ship Sagamore in the vicinity of an Iraqi oil terminal in the northern Persian Gulf at 4 a.m. on August 8, taking computers, cell phones and money from crew members before fleeing the vessel after about 40 minutes on board, according to Lt. John Fage, a spokesman for the Navy's Fifth Fleet in Bahrain.

He said three other ships — the Antigua-flagged Armenia, the North Korean Crystal Wave and the Syrian Sana Star — were also robbed under similar circumstances during a two-hour period starting about 2 a.m. the same day. Other information about the attackers, including their nationalities, was not known, Fage said.

The seaborne robbery occurred about 20 miles off the port of Umm Qasr in an area patrolled jointly by the US Navy and Iraqi sailors. American vessels in the area for routine security operations, including a guided missile destroyer, responded to the attacks, Fage said.

The attack at sea reflects concerns about an increase in crime in Iraq even as political violence ebbs, but Fage played down concerns it signalled a new threat to commercial traffic in the Gulf.

"We do maintain a constant presence. We do maintain a high state of vigilance in conducting security operations with our Iraqi partners," he said in a telephone interview.

Basra, Iraq's second-largest city, which is located near Umm Qasr, has been relatively quiet since a 2008 military crackdown that ended three years of Shiite militia rule, rampant crime and turmoil. The area and the surrounding province contain about 70 percent of Iraq's proven oil reserves of 115 billion barrels.