Boris Johnson, the mayor of London, has said he will consider the possibility of banning cyclists from wearing headphones following the death of six cyclists on the capital's roads in less than two weeks.

Speaking on BBC London radio on Tuesday, Johnson said headphones were an "absolute scourge" and it was "absolutely nuts" to wear them while cycling. He said: "I'm very alarmed about cyclists wearing headphones. I would not be against a prohibition or ban on cyclists wearing headphones. Call me illiberal, but it makes me absolutely terrified to see them bowling along, unable to hear the traffic."

Jenny Jones, a Green party member of the London assembly and a critic of some of Johnson's cycle-related policies, said Johnson was relying on "anecdotal examples". She said: "I won't deny that headphones and smartphones might play a part in some collisions, but on that basis we should be banning all stereos in cars and soundproofed windows in high-performance cars."

Also on Tuesday the head of traffic enforcement for London's police defended an operation in which officers have been stopping dozens of cyclists to advise them to wear high-visibility jackets and helmets. Critics said the scheme, under which police are also targeting infractions by lorry and car drivers, distracted from the primary issues of better cycling infrastructure and the perils of heavy goods vehicles.

DCS Glyn Jones said: "The advice that we give to road users is based on the highway code. What evidential basis lies behind the highway code is a matter for the Department for Transport.

"If I'm truly honest, what we're trying to do here is our best to save lives and keep people safe, both from serious and more minor injuries. Our experience from motorcycles is that the more visible they are, the better."

DCS Jones said the operation, under which 2,500 officers are being deployed to enforce traffic rules in the capital's most notorious accident blackspots, was also focusing on lorries.

"There is a high level of offending by lorries in terms of driver hours or vehicle defects. And in a conflict between a cyclist and a lorry, the cyclist is always going to be the loser, because they are the more vulnerable road users. And I will do anything I can to try and prevent those deaths and serious injuries.

"Since January 2010, more than 50% of cyclists killed on London's roads have died because they've been travelling on the inside of a left-turning HGV. I am not saying it's their fault. What I am saying is when cyclists are approaching a junction on their left and they have an HGV in front or beside them, I would ask the cyclist to consider hanging back, because it would give them more reaction time."

He said he shared Johnson's worries about headphones. "There is, I think, good call for lorries to have audible warning signals when they're turning left, but cyclists with headphones won't hear them. It is a distraction to the cyclist and it makes them less aware of their environment because their hearing is impaired."

Johnson faces pressure to consider a system to restrict lorries' access to central London during peak time, a plan already in force in Paris. On Tuesday Chris Boardman, the former Olympic cyclist and adviser to British Cycling, wrote an open letter to the mayor on the issue. He said: "When I rode alongside you to help you launch your vision for cycling in March this year, you made a verbal promise to look at the successful experiences of Paris and many other cities in restricting the movements of heavy vehicles during peak hours.

"London has an opportunity to emulate and surpass Paris and to lead the way for the other ambitious cycling cities across Britain. Let's not waste this opportunity to do something now. The longer we delay, the more lives will be lost."

On Monday a man, who has not been identified but is believed to have been 61, was killed after his bike and a lorry collided at about noon in Camberwell, south-east London. Last Wednesday a 21-year-old male cyclist, who is also yet to be named, died after a collision with a double-decker bus at the junction of Whitechapel Road and Commercial Road.

Earlier that day Verena Minakhmetova, 24, from Russia, was killed after a lorry hit her bike on the Bow roundabout in east London. And the day before that, Roger William De Klerk, 43, an IT consultant from Forest Hill, was in a collision with a bus outside East Croydon railway station. He died in St George's hospital shortly after the incident.

On 5 November, Francis Golding, 69, an architect, was in a crash with a coach in Southampton Row, central London. He died three days later in St Mary's hospital. Hours earlier Brian Holt, 62, a hospital porter, died at the scene of a collision with a tipper lorry on Mile End Road.