If you were drowning in a river the last thing you would want to see was a lifebelt from the Titanic hurtling towards you.

However, if you were to fall into the River Thames at Osney Island in Oxford, this might be what saves your life.

The Environment Agency, which looks after lifebelts on the river, said the ring, was not actually from the stricken ship.

But a spokesman for the agency said it was important for people to stay safe when walking alongside rivers during the current cold snap.

He said: "We're asking people to be extra vigilant, especially parents as children are still off school. It may look safe, but there are still dangerous areas with thin ice and slippery river banks.

"We would urge all parents not to let their children play near water and ask people walking their pets by rivers to be very careful."

British Waterways, which is responsible for the country's canals, warned people to stay off ice-covered canals.

Simon Ainley, British Waterways' manager for the Oxford and Grand Union canals, said: "At this time of year, it's vital that people are aware of the potential dangers and do not attempt to step on to the ice or let their dogs or children play on or near the edge of canals."