British Airways said none of the 137 passengers was harmed
A British Airways (BA) flight from France made a priority landing at Heathrow after fumes were detected in the passenger cabin.
Flight BA 341 took off from Nice at about 0630 BST on Monday with 137 passengers on board and landed at the west London airport shortly after 0800.
There were no reported injuries among passengers on the flight from Nice.
A spokesman said the captain of the flight requested a "priority landing as a precaution".
Engineers are currently examining the Boeing 757 for clues as to the cause of the incident.
The spokesman said: "The captain of today's BA 341 Nice to Heathrow flight requested a priority landing as a precaution after it was reported that some fumes had been detected in the cabin.
"The 757 with 137 passengers on board landed safely and passengers disembarked as normal."
Emergency services were put on standby as a routine precaution but their help was not needed, he added.
On Sunday a BA flight travelling from Heathrow to Delhi made an emergency landing in Schoenefeld airport, south-east of Berlin, after an electrical fault was detected in its in-flight entertainment system.
In an emergency landing a flight is forced to make an unscheduled stop while in the case of a priority landing the flight's crew request to be placed first in the queue for landing.