Hull CCG said its IT supplier eMBED was investigating after a number of practices were hit by the virus last week.
Patients at one practice reported receiving unsolicited spam from the practice’s account.
The Haxby Group, which runs three practices in the city, said in a statement that its patients had received the spam emails asking for invoice payments. It said the emails appeared to come from the Haxby Group.
‘We would like to assure all our patients that we would never contact you via email for any payments and that if you receive anything that looks like this you should delete it immediately,' it said.
Hull CCG said on Friday the virus, which was sending the bogus invoice requests to practice staff, had been quickly identified and and controlled with support from NHS Digital and that no patient services had been disrupted.
It said anyone receiving a suspicious email should not respond to or click links in it.
A CCG spokeswoman said: ‘NHS Hull CCG’s IT Partner, eMBED has been dealing with a computer virus issue at a number of GP practices in Hull. Once it was identified the virus was quickly controlled, and is being monitored with support from NHS Digital. There has been no reported disruption to patient services and the CCG has kept in regular contact with all practices affected.
‘eMBED is currently investigating reports that a small number of patients at one practice have received unsolicited/spam emails which appear to have come from a practice account.
‘General advice remains that you should be vigilant about any emails that look unusual or that you are not expecting. You should not respond to, or click on links in, emails that you have any suspicions about.’