The delay in providing public health advice to GPs following the poisoning of Sergei Skripal in Salisbury has been deplored by doctors.
Representatives at the British Medical Association (BMA) annual meeting in Brighton criticised the failure to set up a poisons helpline once the nature of the incident was suspected.
GPs were left "guessing in the dark as the worried came seeking advice", the meeting heard.
It took 12 days for them to be told how to manage patients who may have come into contact with the substance which saw Mr Skripal and his daughter taken to hospital.
Delegates backed a motion, proposed by Cardiff and Vale of Glamorgan division, stating that the meeting "deplores the failure of government communication following the Salisbury incident".
Baroness Ilora Finlay, who proposed the motion, said: "When an incident like this happens and we all hope it won't, but we all know it might, concerned people in the periphery of the incident go to the GP."
Healthcare professionals "did their job 100% and more", she added, but "felt that the lack of central information left them guessing in the dark, as the worried came seeking advice".
She called for secrecy to be maintained around such incidents to protect national security, but said a helpline could have been established to provide advice to GPs without disclosing the nature of the substance.
Dr Peter Holden, a member of the Emergency Preparedness, Resilience and Response group, said staff "worked like Trojans" in the aftermath of the attack.
"It took 12 days because we didn't know what we were dealing with and I will defend my colleagues," he said as he spoke against the motion.
"Because when you do know what you're dealing with, you may not want to tell your enemies you know what you're dealing with, because you may want to catch the criminals."
He added that current advice for GPs in such a chemical incident is to "lock your doors".
"Just like A&E locks its doors because you don't want the whole facility contaminated," he added.