MANAMA, Bahrain (AP) _ Iraq said Tuesday its warplanes attacked an oil tanker off Iran, and the two enemies reported air strikes on each other's oil facilities.

Persian Gulf-based salvage and shipping executives meanwhile reported that a tugboat managed by a West German company was sunk in an Iraqi air attack last week, and that four seamen were killed.

An Iraqi military spokesman said in a statement on state-run Baghdad Radio that Iraqi warplanes dealt an ''accurate and effective hit to a large maritime target'' in the gulf waters near Iran early Tuesday.

The Iraqis often use the term large maritime target to refer to oil tankers raided in the northeastern gulf near Iran's Kharg oil terminal.

The shipping sources said they could not confirm the attack.

Iran said its jetfighters bombed Iraq's al-Amiq and al-Bakr oil platforms in the northwestern gulf Tuesday. A statement from the Iranian armed forces said the two platforms sustained ''substantial damage.''

The statement, distributed by the official Iranian news agency IRNA and monitored in Nicosia, Cyprus, said the aircraft returned safely to base.

Earlier Tuesday, Iraq said its warplanes raided pumping stations of two oil fields in Iran's southern Khuzistan province to ''impede repair work on damage'' caused in a previous raid.

The warplanes struck and ''further destroyed'' the two facilities in the Ahwaz and Maroun oilfields, the Iraqi military spokesman said on Baghdad Radio, which was monitored in Bahrain.

The same pumping stations were reported raided Friday. Iraq has vowed to destroy Iran's oil resources to force it to accept a negotiated settlement to their war, which has been going on since September 1980. The death toll on both sides is estimated to be in excess of 100,000.

Claims by the two sides usually cannot be confirmed because reporters are rarely allowed near the battlefront.

The Iraqis have been raiding tankers and freighters near Kharg since February 1984.

The shipping sources said the 500-ton tugboat Adil Abu was hit last week by an Exocet missile fired by an Iraqi jet 70 miles southeast of Kharg.

The sources said three Filipino seamen and a West German chief engineer died in the attack. They identified the German only as Uwe Muus. The names of the Filipino victims were not available.

Adil Abu was operated by the West German shipping agency Seetrans Offshore Ltd. to serve offshore oil facilities and tankers.

The Exocet probably was aimed at a disabled supertanker under tow in the vicinity, and hit the tugboat by mistake, the sources said.