Hundreds of people have risked the possibility of eye contact on the London Underground by riding half-naked.

Bare-legged people were spotted across the tube network for the 10th annual No Trousers Tube Ride.

Crowds met outside the National Gallery in Trafalgar Square on Sunday before heading below ground and boarding trains on different tube lines.

More than 100 people piled onto the Piccadilly Line, but struggled to remove their trousers due to the volume of people travelling.

Regular travellers were left surprised by the part-clothed passengers. Credit: PA

Regular passengers were could not resist looking up from their phones and books as men and women sat in their brightly-coloured underwear talking or reading, or taking pictures of each other.

After changing to the Jubilee Line at Green Park, the group got off at Canary Wharf to do some aerobics on the platform before jumping on another train.

Other groups set off for London landmarks, including one heading to Parliament.

The event formed part of No Trousers Tube Ride. Credit: PA

The event is part of the worldwide No Pants Subway Ride, which began in New York in 2002 and has since spread to over 60 cities around the globe including Tokyo, Jerusalem and Moscow.

The London event was organised by the Stiff Upper Lip Society, which asked participants to "avoid thongs/budgie-smugglers/anything see-through though, as we aim to amuse, not offend, fellow Underground users".

One of the organisers, Farhan Rasheed, said there was not really an aim to the event, it was just a bit of fun.

No Pants Subway Ride originated in New York in 2002. Credit: PA

He added: "There is no point to it, we are not campaigning or raising awareness of anything.

"People just have fun doing it, it's a bit of a nonsense day out.

"You very rarely get people who are offended. It's London and London is used to this stuff, they take it in their stride and get back to their book."