TOKYO/WASHINGTON: Boeing Co's 787 Dreamliner jet suffered a cracked cockpit window and an oil leak on separate flights in Japan on Friday - the latest in a series of incidents to test confidence in the sophisticated new aircraft.

All Nippon Airways Co said a domestic flight from Tokyo landed safely at Matsuyama airport in western Japan after a crack developed on the cockpit windscreen, and the plane's return to Tokyo was cancelled.

The same airline later said oil was found leaking from an engine of a 787 Dreamliner after the plane landed at Miyazaki airport in southern Japan. An airline spokeswoman said that return flight to Tokyo's Haneda airport was also cancelled while the leak was investigated. No one was injured in either incident.

The Dreamliner, the world's first carbon-composite airliner, which has a list price of $207 million, has been beset by problems this week.

U.S. transportation officials will hold a press conference in Washington at 0930 EDT (1430 GMT) to discuss issues related to recent electrical problems on the new plane, one person familiar with the matter told Reuters. Bloomberg News said the U.S. Federal Aviation Administration would announce a review into the jet's power system at that news conference.

U.S. regulators have raised questions about the plane's reliability on long transocean routes, the Wall Street Journal reported.

The 787 Dreamliner made its first commercial flight in late-2011, after a series of production delays put deliveries more than three years behind schedule. By the end of last year, Boeing had sold 848 Dreamliners, and delivered 49.

Earlier this week, a battery fire caused damage to an empty 787 jet operated by Japan Airlines while it was on the ground at Boston airport. The next day, another JAL 787 spilled 40 gallons of fuel onto the taxiway at the same airport after a problem that caused a valve to open, forcing the plane to delay its departure. On Wednesday, ANA cancelled a domestic Dreamliner flight due to a brake-control computer glitch.

Boeing's top Dreamliner engineer, Mike Sinnett, was rolled out midweek to defend the 787, saying the plane's problem rates were no higher than with Boeing's successful 777 jet.

ANA said crew noticed a spider web-like crack in a window in front of the pilot's seat about 70 minutes into Friday's flight, which was close to its destination.

"Cracks appear a few times every year in other planes. We don't see this as a sign of a fundamental problem" with Boeing aircraft, a spokesman for the airline said.

On the later flight, the ANA spokeswoman said she could not specify how much oil leaked from the engine.

The latest incidents came just hours before ANA was due to launch its maiden service between Tokyo and San Jose, California with the Dreamliner. That flight was due to leave Tokyo at 0830 GMT, returning to Japan after an around 90-minute turnaround in the United States.

ANA and JAL together fly 24 of the 49 Dreamliners delivered to end-December.

In India - where state-owned Air India has taken delivery of six Dreamliner jets and has more on order - a senior official at the aviation regulator said there was concern at the recent spate of Dreamliner glitches. The Directorate General of Civil Aviation has not ordered any Dreamliner checks for now, but is waiting for a safety report from the U.S. National Transportation Safety Board, the official said.

Air India spokesman K. Swaminathan told Reuters that the airline's debut Dreamliner flight from India to Paris on Thursday went without a hitch.

One of Boeing's chief innovations with the 787 is its use of electrical power to run on-board functions such as hydraulics and air conditioning, instead of relying on heavier pneumatic systems used on other planes. The weight savings make the 787 more fuel efficient, a big advantage for airlines battling high jet fuel costs.

To power the electrical system, the 787 uses generators attached to the plane's engines, which produce about 1.5 megawatts of power, enough to power about 300 hot water heaters. The system uses high-voltage distribution panels and powerful batteries, such as the one that caught fire in Boston on Monday.

Makoto Yoda, president of Japanese battery maker GS Yuasa Corp, which makes the Dreamliner batteries, said his company was looking into Monday's fire, and was sending a team of engineers to cooperate with the U.S. investigation.