SEPANG, Malaysia — A Chinese satellite spotted an object in the southern Indian Ocean in an area that has become the focus of a multinational effort to find the Malaysia Airlines airliner that disappeared March 8, Chinese authorities said Saturday.
The object is about 74 feet long and 43 feet, wide, China’s State Administration of Science, Technology and Industry for National Defense said on its website. It was spotted Tuesday about 75 miles to the south and west of objects seen two days earlier by a commercial satellite.
Defense Minister Hishammuddin Hussein of Malaysia told reporters that the Chinese were sending ships to try to locate it. The object is in the area of one of two possible routes that investigators say they think Flight 370 took.
The two-week-long search for the missing Boeing 777-200 has been plagued by sightings of debris that later proved not to belong to the aircraft, including an earlier Chinese satellite image that proved erroneous.
The hunt for any traces of the plane has been most intense in a section of the southern Indian Ocean about 1,500 miles off the coast southwest of Perth, the capital of Western Australia.
On Thursday, the Australian prime minister, Tony Abbott, said the commercial satellite had spotted two large, indistinct objects floating in the area that might be wreckage from the aircraft. But searches by planes and ships combing the waters have failed to find the objects.
A second ultralong-range commercial jet, a Gulfstream G5, joined the search off Western Australia. The two commercial jets now hired to help look for the plane can spend more time at the search site than Australia’s military aircraft, the Australian Maritime Safety Authority said in an e-mailed statement Saturday.
“The ultralong-range commercial jets have an endurance of approximately five hours of search time,” the authority said. The Royal Australian Air Force P-3 Orion aircraft can spend just two hours over the site before they must return to their onshore base, the authority has said.
The Gulfstream G5 jet, a Bombardier Global Express jet, and a Royal Australian Air Force P3 Orion have been flying out from the Royal Australian Air Force base, Pearce, 22 miles north of Perth, said Sam Cardwell, a spokesman for the Australian Maritime Safety Authority. Another three aircraft left for the search area later on Saturday.
A total of seven aircraft have become involved in the search: three Royal Australian Air Force P-3 Orion planes, a New Zealand P-3 Orion, a US Navy Poseidon P-8 surveillance plane, and the two commercial aircraft.
At least two merchant ships are also in the area, and the Australian navy’s Success was expected to arrive late Saturday afternoon, according to the Australian Maritime Safety Authority, which is based in Canberra, the national capital.
Also Saturday, two Chinese Il-76 Ilyushin transport aircraft left an air base near the Malaysian capital, Kuala Lumpur, en route to Australia to take part in the search, the official Xinhua News Agency said. Britain is dispatching a naval hydrographic survey ship, the Echo, and Japan is sending two P-3 Orion aircraft.
The authority said Saturday’s search would cover 13,900 square miles, and 10 volunteers from Western Australia’s State Emergency Services were helping as spotters on the commercial jets. Cardwell, the safety authority spokesman, said the volunteers were trained in search techniques including judging distances and spotting debris.
In the northern corridor, which stretches from Thailand to the shores of the Caspian Sea in Central Asia, countries have been searching radar records for any sign that the plane crossed their airspace. On Saturday Hishammuddin said that seven countries — China, Laos, India, Pakistan, Myanmar, Kyrgyzstan, and Kazakhstan — had not seen anything.
“Based on preliminary analysis, there have been no sightings of the aircraft on their radars,” he said at a news conference in a hotel at Kuala Lumpur International Airport.
The Pentagon said Friday that it was considering a request from Hishammuddin to provide towable underwater listening devices to help search for the airliner. The Malaysian defense chief made the request for the underwater surveillance equipment in a telephone call with Defense Secretary Chuck Hagel, the Pentagon said in a statement.
The United States also provided Friday the first details of the costs it is incurring for its portion of the search operation.
The Pentagon has so far spent $2.5 million of the $4 million set aside to cover the costs of the US ships and aircraft participating in the search through early April, a Defense Department spokesman said.
Additional funds could be added once that initial money is spent, US officials said. The spokesman said the United States would not seek reimbursement from the Malaysian government.
In a statement on its website announcing China’s find, the State Administration of Science, Technology and Industry for National Defense did not explain why it took four days to release the information. But there was a similar delay in the release of the Australian satellite images because experts needed time to examine them.
The Boeing 777-200 is about 209 feet long, with a wingspan of 199 feet and a fuselage about 20 feet in diameter, according to Boeing’s website.
Malaysian authorities have not ruled out any possible explanation for what happened to the jet, but have said the evidence so far suggests it was deliberately turned back across Malaysia to the Strait of Malacca, with its communications systems disabled. They are unsure what happened next.