LONDON – Traces of radiation have been found at a dozen sites in Britain and five jets were being investigated for possible contamination as authorities widened their investigation into the poisoning of a former Russian spy, the country’s top law enforcement official told Parliament on Thursday.

A coroner formally opened an inquest into the poisoning of Alexander Litvinenko, who died on Nov. 23 after falling ill more than three weeks earlier. It was quickly adjourned so police could continue their investigation, but three pathologists were expected to participate in an autopsy Friday at Royal London Hospital.

In Moscow, meanwhile, doctors said they believed Yegor Gaidar, a former premier and head of a liberal opposition party, may also have been poisoned during a conference Nov. 24 in Ireland, his spokesman Valery Natarov told The Associated Press.

Gaidar, 50, became violently ill and was rushed to a hospital in Ireland, but has since returned to Russia where he was improving.

Natarov told the AP that doctors were unable to “detect any natural substance known to them” in Gaidar’s body, leading them to believe he may have been poisoned. However, they have not been able to determine what caused specifically his illness and have asked medical experts in Ireland for more information on his condition immediately after he became sick.

A spokeswoman for the Irish Department of Foreign Affairs, speaking on customary condition of anonymity, said Thursday it had not been contacted by the Russian authorities about the doctors’ opinions. A day earlier, the department said authorities had “received no evidence of anything untoward” about the case.

High doses of polonium-210 – a rare radioactive element usually made in specialized nuclear facilities – were found in Litvinenko’s body after his death. Investigators are now checking places visited by the former KGB agent and others who had contact with him in the weeks before he fell ill on Nov. 1.

Home Secretary John Reid told Parliament that “around 24 venues” have been or are being monitored as part of the investigation, and that experts had confirmed traces of radioactive contamination at “around 12 of these venues.”

Reid told lawmakers that officials believed the risk to public health to be low. He said 1,700 calls had been made to the National Health Service, and 69 people were referred to the Health Protection Agency. Of those, 18 who may have been exposed to polonium-210 have been referred to specialist clinics, but all urine tests so far have been negative, he said.