A British Airways plane had to return to Heathrow airport today with smoke billowing from the aircraft.

With eyewitnesses reporting seeing an engine on fire, the Airbus A319 plane made an emergency landing, with the 75 passengers and crew all safely evacuated via the emergency chutes.

London Ambulance service later reported that three people had been treated for minor injuries from the flight, which had taken off from Heathrow for Oslo this morning.

Both the northern and southern runways at Heathrow were closed after the incident, although flights were able to resume shortly afterwards from the southern runway.

Eyewitnesses described seeing smoke coming from the plane, with the right engine on fire.

Clive Cook, who lives on the Heathrow flight path, told Sky News: "The actual engine itself was on fire.

"This plane was coming over and suddenly the tone of the engine changed dramatically, and I could almost say it sounded as if it was like a blowout, or an explosion.

"I'm absolutely certain that as it came through the clouds, and I looked up ... the right engine was on fire, it wasn't smoking, it was actually on fire."

Mr Cook said he saw the plane over the Thames at Battersea as he was taking his daughter to nursery.

Another eyewitness, named only as Jamie, was working in his garden near to Stamford Bridge, Chelsea, when he saw the plane.

He told Sky News: "All of a sudden we heard this almighty noise. It was like a fire jet going over. We could just see the right engine on fire - it was absolutely horrendous to see.

"You don't see things like that every day, it's incredible really.

"Your thoughts are with the people, If we could hear it that badly then what were the people going through on that plane?"

He said he thought the plane was just a few thousand feet above the ground and added: "It was below the clouds at this stage. To see an aircraft on fire - it wasn't good to watch."

A BA statement said: " BA762, Heathrow to Oslo service, returned back to Heathrow shortly after take-off due to a technical fault. The Airbus A319 aircraft was carrying 75 customers.

"The aircraft landed safely and emergency slides were deployed and we are currently caring for our customers. Emergency services attended the aircraft. We will be carrying out a full investigation into the incident."

There was speculation that the aircraft may have run into a flock of birds but there was no official confirmation of this.

Birdstrikes are a serious problem for aircraft and have been known to bring planes down.

Following today's incident, passengers on resumed flights at Heathrow were warned to expect delays of up to 60 minutes and extended aircraft taxiing times.

BA said the plane, with two pilots and three cabin crew aboard, had taken off for Oslo at 8.16am and had landed back at Heathrow just after 8.40am.

"The passengers are being looked after at the moment," said a BA spokesman.

The incident is being investigated by the Air Accidents Investigation Branch.

Captain Mark Searle, chairman of airline pilots' association Balpa, said: "This was a professional job done by professional people. As pilots we spend our whole career training to manage incidents such as this in order to avoid an incident becoming a disaster.

"Balpa representatives will be assisting the pilots involved in this incident and providing whatever support they need. And, as always, we will all learn whatever lessons we can."