Stunned passengers watch as Madonna gets off economy flight (loaded with Louis Vuitton luggage) after plane makes surprise landing in Porto (Details, pics)

Stunned passengers were left open-mouthed as they watched Madonna get off an economy flight - loaded with her Louis Vuitton luggage - after their plane was diverted on its way to Lisbon.

The music legend, worth around £600 million, was flying from Heathrow with Air Portugal earlier this week when the crew told passengers that the plane had to refuel in Porto instead.

The American, 59, looked tired as she wore a long, black and white multi-checked coat, a monochrome striped scarf and hid her make-up free face under a grey fedora hat.

She had been hiding completely unrecognised in the cheap seats - which cost from just £42 instead of £180 for business class tickets - until the flight landed in Porto and her agent whisked her through business class to the front of the plane.

An onlooker said: 'We'd been on the ground for about 20 minutes when I saw her assistant speaking with crew members at the front of the plane.'

Then I noticed the crew carrying all this Louis Vuitton luggage past me down the aisle too. And Madonna literally walked by me. I couldn't believe it.'

She had no make-up on but I Googled her and I discovered that she's recently bought a place in Lisbon, so her being on the flight suddenly made sense.

'I messaged my partner saying, 'I think Madonna is on my flight!'

'She looked tired as she sat and waited at the front of the plane for about half an hour. I could barely see her face, she was constantly turning away or hiding her face in her scarf.'

She didn't say or do anything while her agent was on her phone. Madonna was just sitting and waiting.

'Then she got off the plane and I saw her get on to an airport bus. I'd heard her agent saying that her car was waiting out front - they must have meant outside the airport.

'The assistant appeared to have told the crew she was Madonna but they remained professional and didn't react. No one else appeared to recognise the Holiday superstar in their midst.

The source continued: 'Then an old woman asked why two women had left the flight at Porto. A female crew member whispered to her that it was Madonna. She was gobsmacked!

'The lunchtime flight sat on the Porto runway for about an hour before flying on to Lisbon.

Air Portugal flights usually arrive in the city in 2 hours and 35 minutes, a quicker journey than it takes with rivals Ryan Air and easy jet.

The rest of the passengers eventually arrived in Lisbon three hours late yesterday evening.

The Like A Virgin superstar now divides her time between Portugal, the US and the UK, where her eldest son Rocco Ritchie, 17, lives with his director father Guy.

Her son David Banda - who she adopted from Malawi in 2006 - joined Benfica youth football academy earlier this year, where his 'prodigious talents' were said to have 'impressed everyone' in his first week.

Madonna has now left the confines of a Lisbon hotel and has moved into her own home in Sintra, 17 miles from the Portuguese capital.

A local media report in August said: 'Madonna is no longer a tourist, she now lives in Lisbon.'

It came after news revealed that she was 'uprooting' her family from their New York home to start a new life and to give her children 'every opportunity'.