Qatar Airways said on Friday it had taken one of its 787 Dreamliners out of service following what it described as a "minor" technical issue, as pressure mounted on Boeing over possible new electrical problems with the advanced jet.
The airline and Boeing, the airplane's manufacturer, declined to give further details but industry sources said they were treating seriously reports that the aircraft had been grounded for days after smoke was seen near an electrical panel.
The 787 has suffered a spate of mishaps in recent weeks.
According to web-tracking service Flightaware, the aircraft, registered as A7-BCB, has not flown since Sunday, an unsually long downtime for a long-haul jet designed to save fuel bills.
Qatar Airways confirmed an aircraft had been taken out of service, but said no flights had been cancelled as a result.
"This is a minor issue for us, and not an incident, so we are not commenting," an airline spokeswoman said.
A spokeswoman for Boeing said, "We request that you channel all your enquiries to Qatar Airways."
Two people familar with the matter, asking not to be identified, said smoke had been reported near an electrical compartment while the jet was on the ground in Doha. A failure in a similar bay caused an fire during a test flight in 2010.
A fire-brigade supervisor in Doha said it did not have any record of an incident with an airport-related call last week.
India's aviation regulator said earlier it had started an investigation after an oven in a 787 operated by Air India overheated during a domestic flight, causing smoke.
There was no interruption to services.
Japan's ANA, which operates the world's biggest fleet of Dreamliners, also said on Friday it had found damage to the battery wiring on two 787 locator beacons.
Tests have been ordered on the beacons after a parked Ethiopian Airlines-owned 787 Dreamliner caught fire at London's Heathrow this month, causing extensive damage to the plane.
The global fleet of Dreamliners was grounded for three months earlier this year due to battery-related incidents.
Aviation experts say it is common for the reported number of incidents to rise when an aircraft is in the spotlight.
Aircraft regularly suffer glitches that go unreported and rarely pose a direct theat to safety.
However, aviation experts say US and British authorities investigating the previous fires may seek to establish whether anything can be learned from a pattern of reported incidents connected in various ways to the jet's electrical systems.
Boeing chief executive Jim McNerney said this week he remained "highly confident" in the future of the 787 Dreamliner programme and the integrity of the company's newest airplane.
The 787 incorporates a raft of changes in the way passenger jets are designed, including greater use of electrical systems that save weight compared to older hydraulics. It is the first passenger jet built mainly from lightweight carbon-composites.