DAREDEVILS who jump into the River Thames have been warned of dangers lurking beneath the water.

Oxford city councillor David Henwood has highlighted a problem with hefty rubbish hiding under the surface, after pulling six rusty bikes from the river in East Oxford, ahead of the Oxford City Royal Regatta.

When preparing for the event, the Cowley ward member discovered the bikes dumped near Donnington Bridge, which he said was particularly worrying as some people dive from there in summer months. 

He said: "This is incredibly dangerous as occasionally people jump from the bridge, which we discourage as the river is low at this point.

"We were all young once and all want to be a bit mad once, I can appreciate that. But we all should be aware of what's underneath the bridges: it's where people throw in items like this. It's a convenient place to drop something."

He noted a tragic incident in 2012 in which 15 -year-old Mohammed Hussain died after jumping into the river from Donnington Bridge.

Safety risks of bridge jumping have also been stressed previously regarding the River Cherwell, after 40 people hurt themselves plunging in from Magdalen Bridge during May Day 2005 celebrations.

In past years authorities put posters up stating: "Broken bottles? Shopping trolleys? Rusty cans? Discarded syringes? We don't know what's in the water below Magdalen Bridge."

Mr Henwood, a member of Falcon Rowing and Canoeing Club, helped to haul the bikes from the water last week while preparing for Oxford City Royal Regatta.

The annual sporting event, organised by City of Oxford Rowing Club, will see about 500 crews take to the Thames this weekend.

He said he has seen bikes in the river previously, but could not remember finding so many in one spot before.

Speaking about possible reasons for the strange discovery, he added: "It's possible that people do it for a laugh. There is another view that people might have stolen them from the city centre and then dump them.

"Whatever the reason, it simply demonstrates that some people still have a lot to learn."

Mr Henwood also raised concerns about environmental implications of using the river as a waste bin.

He said: "Now that open water swimming, rowing and boating are gaining popularity and more of us are looking towards the river for recreation, we need to look after this important asset. Now just for our own needs but also for the environment, which we share with other wildlife."

He suggested that 'bike banks' could be a potential solution, where residents can leave unwanted bikes for others to buy for a small fee.

Similar bike recycling schemes already exist in Yorkshire and Exeter.