DUBAI, United Arab Emirates — Despite the growing presence of U.S. and other foreign navies, civilian shipping in the Persian Gulf on Wednesday came under the most concentrated attack since warfare erupted between Iran and Iraq seven years ago.
Gulf shipping sources said that Iranian Revolutionary Guards operating in speedboats attacked five civilian ships, while an Iranian frigate hit a sixth vessel with naval artillery.
Iraq, meanwhile, sent its fighter-bombers into action over the gulf for the fifth consecutive day, reporting hits on two Iranian tankers. In all, the Baghdad regime in recent days claims to have hit 11 Iranian ships that ferry oil from the Kharg Island oil terminal to foreign vessels farther south for shipment out of the gulf.
Shipping sources also reported that one of the Iraqi planes hit and sank a third ship, a Panamanian-flag supply vessel, the Big Orange XIV, near the Iranian coast Wednesday. There was no word of survivors from the 170-foot vessel, which operated out of the United Arab Emirates port of Sharjah.
Shipping officials said the attacks had reached an unprecedented level as Iran carefully retaliated for every announced Iraqi attack against Iranian shipping.
"The policy of blow-for-blow retaliation will be followed in a calculated way," Iranian Prime Minister Hussein Moussavi said after a Cabinet session in Tehran, according to Tehran radio.
Moussavi said Iran will never bow to American pressure to accept a cease-fire in the Persian Gulf War.
The Iranian and Iraqi attacks in the gulf appeared to be part of the maneuvering surrounding efforts to force Iran to accept a U.N. cease-fire resolution adopted July 20.
The United States said Tuesday that if Iran refuses to accept the truce by Friday, it will seek adoption of a second measure imposing a worldwide arms embargo against Iran.
Iran and Iraq had been observing a six-week de facto truce in the tanker war since the U.N. resolution was adopted. But Iraq, apparently impatient with the diplomatic maneuvering by Iran's Muslim fundamentalist leaders, resumed its air raids on Iran's offshore oil installations Saturday. Iran had continued to export more than 2 million barrels of oil a day, earning foreign exchange to replenish the country's depleted war chest.
The Iranian gunboat attacks, presumed to have been carried out by Iranian Revolutionary Guards, struck Japanese, Cypriot, Greek and Spanish vessels. The raids followed a now-familiar pattern of what amounts to naval guerrilla warfare, with speedboats operating out of tiny offshore islands spraying foreign shipping with machine-gun fire and rocket-propelled grenades but causing no casualties.
Late Wednesday, a Japanese tanker was hit with three Iranian rockets off the coast of Dubai, Japanese shipping sources in Tokyo told Reuters news service.
They said the 180,200-ton Nisshin Maru was attacked even though it was carrying Iranian oil. The tanker was reported to be sailing toward the United Arab Emirates port of Fujaira in the Gulf of Oman.
Earlier Wednesday, a South Korean ship was hit off Dubai by a 4 1/2-inch shell fired by a Iranian navy frigate, the shipping sources said. The shell caused extensive damage but no injuries.
The apparent goal of the Ayatollah Ruhollah Khomeini's government is to put pressure on Iraq through its allies among the gulf's Arab states, which are increasingly fearful that Iran's interference with civilian shipping will cut into their trade.
Similar fears last year prompted Kuwait to request American naval escorts for its oil tankers. Six escort missions have been completed since the start of the operation last month.
"While the Iranian attacks are really pinpricks, it is worrisome that the presence of all these American warships has no deterrent effect on either side," said one shipping source.
In addition to the attacks on maritime targets, Iran said it shelled economic and industrial targets in the Iraqi cities of Basra, Amarah, Zubayr and Qala Diza.
Iraq, for its part, said it bombed an engineering plant and a power station in the central Iranian town of Awa and a power plant in Kanjara. The oil field of Agha Jara south of Avhaz was set on fire, the Iraqis said.
In Santa Barbara, meanwhile, White House spokesman Dan Howard denied a United Press International report that the United States has been assisting Iraq in its latest attacks by providing it with intelligence gathered by American-manned AWACS radar surveillance planes based in Saudi Arabia.