A flight was forced to make an emergency landing at London Heathrow after a toilet leak threatened to flood the cabin.

The Delta Air Lines flight from Paris-Charles de Gaulle to Seattle-Tacoma International landed in London on August 13 after an onboard lavatory suffered a mechanical fault just 40 minutes into the trip.

The toilet then began leaking out of the cubicle into the cabin of the Airbus A330-900, according to reports.

It is not clear whether the liquid was hazardous waste or fresh water from a faucet.

At the time, the flight was carrying 209 passengers and 13 crew members.

Flight 81 was then diverted to Heathrow where it declared an emergency, due to being overweight.

Overweight landings often happen when unexpected emergencies mean planes cannot stay airborne to burn fuel.

The plane landed safely and technical teams from Delta Airlines were then able to complete a repair to the lavatory before continuing on the journey to Seattle.

However, according to Fox News, the plane was forced to make another detour, this time landing in New York’s JFK Airport. This was due to the crew’s working limit being reached.

An airline spokesperson told the aviation outlet Simply Flying: "We apologize to our customers for their experience and delay on Delta Flight 81 from Paris-Charles de Gaulle to Seattle, which diverted to London Heathrow after the crew reported a mechanical issue involving an onboard lavatory. This is not the experience we strive to provide, and we're focused on getting our customers to their destinations as quickly and safely as possible."

The Standard has contacted Delta Airlines for comment.