TOKYO, June 4 (Xinhua) -- The Japanese government has ended a major search operation for an Air Self-Defense Force F-35A stealth fighter that crashed into the Pacific Ocean off northern Japan two month ago, Defense Minister Takeshi Iwaya said on Tuesday.

Once their safety had been ensured, Iwaya indicated that 12 F-35A currently deployed at the Misawa Air Base in Aomori Prefecture would be allowed to resume flights soon.

So far, the search for the missing plane, which went down in waters off Aomori Prefecture on April 9, has only recovered fragments of the plane, including parts of the engine and the main wing.

The pilot and the stealth fighter's black box recorder have yet to be accounted for.

Iwaya said Tuesday that he believes it is unlikely that any other pieces of the plane will be found that might provide clues as to the plane's crash, although the minister said a smaller sized search operation would continue across a wider sized area, in a bid, if possible, to retrieve some of the plane's highly classified technology.

As to the resumption of the flights of the other F35A's, the ASDF has said that flights could be resumed once the data received from the three other jets taking part in the drill when the crash happened, reveals the jets' safety measures are not in any way compromised.

Part of the accident has been recreated based on the data which can be shared and collated from the other planes, as well as from radar on the ground, ASDF officials said.

Iwaya indicated that owing to this process, the reasons or possible cause of the accident have been "narrowed down," although said a precise date for the resumption of the flights had not been decided on yet.

The crashed plane had been flying with three other F-35As on a training mission and according to ASDF officials there were no reports of problems from the plane before it went missing.

The missing plane took off from Misawa Air Base in northeastern Japan at around 7 p.m. on April 9, the ASDF said.

It was flying off the coast of Aomori Prefecture about 135 km east of the base when radar contact was lost less than 30 minutes after takeoff, the ASDF said.

Military experts have questioned Japanese pilots' ability to fly the 5th generation multi-role stealth fighter, intimating that the cutting-edge aircraft requires a significant amount of knowledge and expertise to fly.

General Toshimichi Nagaiwa, a former Air Self-Defense Force Lieutenant, told Japan's public broadcaster NHK that the crash poses a significant problem to the deployment of the jets in Japan and for them to become Japan's mainstay fighters.

The Air Self-Defense Force began deploying F-35A jets at its Misawa base in Aomori Prefecture, northern Japan, in January last year.

A new F-35 squadron has been formed at the base with 80 personnel and the Japanese government plans to bolster its fleet of F-35s with the acquisition of a total of 105 F-35As and 42 of the short take-off variant F-35B stealth fighters.

Each F-35A comes with a price tag of around 10 billion yen (90 million U.S. dollars).

The jets, the Pentagon's most sophisticated 5th generation multi-role stealth fighters and most expensive weapons system, are supposed to replace Japan's fleet of F-15 and aging F-4 fighter planes.

But Nagaiwa asserted that Japanese pilots need greater skills and more knowledge to be able to fly the ultra-advanced jets and that it had yet to be determined whether the crashed jet, which had made two emergency landings in the last two years, was itself faulty, or if human error was the cause of the crash.

The jet, the first to be assembled in Japan at Mitsubishi Heavy Industries Ltd.'s plant in Aichi Prefecture, was forced to abort a test flight after a cooling system malfunction, Japan's Defense Ministry has said.

It also said that a position indicator malfunction also occurred in the jet when it was flying in bad weather.

Underscoring rising concerns about the jets' safety, a Japanese ASDF team looking into the the cause of the accident said it suspects the pilot, a major in his 40s who had logged 3,200 hours of flying time including around 60 hours specifically flying F-35As, may have noticed some kind of "abnormality" before the plane crashed.

The Defense Ministry has since said that the plane likely crashed before the pilot had time to eject, as its ejection system sends out an alert when a pilot ejects, although he had radioed three other F-35A pilots also taking part in the combat drill saying he was aborting the mission.

The 5th generation jets are co-developed by nine countries including the United States, Britain and Italy and are produced by U.S. defense company Lockheed Martin Corp. and cost around 50,000 U.S. dollars per hour to fly.