The doctors union, the British Medical Association (BMA), has warned that potentially serious health problems could be missed by GPs, and lead to patients being harmed, when a new online booking system is launched across England on Wednesday.

But Health Secretary Wes Streeting says ministers are putting the interests of patients first and had already agreed clear safeguards with the union.

The system will allow patients wanting an on-the-day GP appointment, or a call from a clinician, to make a request online throughout the day.

The facility is already available in many practices and is designed to reduce long waits on the phone during the so-called ‘8am scramble’.

The BMA says the government must halt the rollout of the online booking plan to allow changes to be put in place.

The union argues that online systems cannot distinguish adequately between urgent and non-urgent patient messages, and this could lead to potentially serious cases being delayed.

The BMA has also warned there would be a “potential online triage tsunami” with no additional workforce to cope with the extra demand.

Union leaders say more should be done to provide safeguards, such as allowing practices to temporarily switch off the online booking mechanism if staff are struggling to handle patient numbers.

The union has warned that if the government does not amend the scheme, a formal dispute will be declared. This could lead to a “work to rule” situation, similar to what was introduced in a previous dispute during which GPs limited patient appointments to the minimum required under their contract.

But ministers argue that the BMA had agreed to the introduction of online booking as part of a new negotiated contract in England. They point out that many GPs already offer the service.

Wes Streeting, Secretary of State for Health and Social Care, said it was “absurd” that in 2025 many patients can’t request appointments online.

“If you can book a hair appointment online, you should be able to book an NHS appointment too. We have agreed clear safeguards, where patients will be directed to phone up or attend in person for urgent appointments. The BMA knows this. This government will always put the interests of patients first, and we will not stand for our NHS being held back in the analogue age.”

Dr Katie Bramall-Stainer, chair of the BMA GP committee, said the changes were agreed to “on the condition that ‘necessary safeguards’ would be put in place” before Wednesday 1 October.

“This was agreed – in writing – with government… and NHSE in February this year. Now almost eight months later, it is deeply disappointing to see promises broken,” she added.

She said ministers had been warned that the changes would lead to “hospital-style waiting lists in general practice” which could “reduce face-to-face GP appointments”.

Mr Streeting said that that 2,000 extra GPs had already been hired across England and that patient satisfaction with their GPs was on the up.

Officials said that surgeries which had implemented the changes had reported reduced waiting times for appointments.