Cyclists in London have taken to social media this morning to express their concern after anti-terrorism barriers were installed overnight on several bridges across the Thames in response to Saturday evening’s terrorist attack, taking away space from cycle lanes.

Several photos posted to platforms including Twitter show that the barriers, placed next to the kerb on Lambeth, Waterloo, and Westminster bridges, have reduced the width of cycle lanes in places, leaving little or no safe space for cyclists.

Campaigners say that while the installation of the barriers is “understandable and right,” there is a risk that they will increase the danger to the thousands of cyclists who ride across London’s bridges each day.

Three terrorists used a rented van to mount a pavement on London Bridge on Saturday evening, crashing into people walking across the bridge, then abandoned the vehicle and began stabbing people enjoying an evening out in the popular Borough Market area.

Seven people were killed and dozens injured, some critically, although as yet no separate figures have been released relating to casualties sustained as a result of the van being driven into people on the bridge.

The attack comes less than three months after Khalid Masood drove a car onto the pavement at Westminster Bridge in March, killing four people and injuring around 50 more.

Here are some posts from Twitter regarding the emergency barriers that have appeared this morning.

Sam Jones, campaigns co-ordinator at the charity Cycling UK, told road.cc: “Given the number, scale and type of attacks in the last nine weeks, it is understandable and right that the police and Transport for London are putting in measures to protect key points of infrastructure from likely threats.”

He said that the charity had already been approached by one member this morning who was concerned about the impact of the barriers on cycle lanes at the locations in question.

“Having been contacted by the membership about what this means for the current cycling infrastructure, there is concern what this might mean for protecting our must vulnerable road users on their daily and regular journeys as well,” he said.

“We are speaking with the London Cycling Campaign (LCC) and will work with LCC and the relevant local bodies to see what provisions they are planning to make for those who cycle across these bridges.”

Matt Winfield, London deputydirector at the charity Sustrans, said: “We are grateful that the Metropolitan Police and Transport for London are working to find ways to protect and reassure Londoners after the terrible attack last weekend. The safety of all Londoners is paramount.

“Being able to walk and cycle safely is crucial to London’s vitality. A small change to the barriers so that they protect people on bikes as well as pedestrians would ensure the brides are safer for cycling too. A long-term solution would also have to meet the needs of the growing number of Londoners who travel by bike.

“Cycling is part of the solution to many of the challenges we face in cities – from air pollution, road safety, obesity and inactivity. It is essential we keep encouraging more people to cycle and support those who already do so.”

A spokesman for TfL told the London Evening Standard that the additional security measures had been implemented by the Metropolitan Police Service.

“We are aware of the hostile vehicle mitigation measures being installed by the Met on some of London’s bridges and are supporting them with this work,” he said.

Recent years have seen kerbed cycle lanes installed on a number of bridges across the Thames in Central London including Vauxhall, Westminster and Blackfriars, as part of TfL’s Cycle Superhighways programme.

Installation of the separated infrastructure followed years of campaigning by groups including LCC.

In a statement posted to Twitter, it expressed its full support for the security measures put in place last night but also urged that the safety of cyclists be taken into account.