The bird flu strain found on duck farm in East Yorkshire is H5N8, the Department for Environment, Food and Rural Affairs has confirmed.
The strain is the same as was detected at an egg farm in the Netherlands.
Defra had already ruled out the H5N1 form, which is deadly to humans.
About 6,000 ducks were ordered to be killed and a six-mile surveillance zone is going up around the farm after the discovery on Sunday, 16 November.
A Defra statement confirmed a cull was underway at the farm.
"As part of our robust action in response to the confirmed case of avian flu, the culling of 6,000 ducks is underway on the affected farm in east Yorkshire," the department said.
"The cull is to prevent the spread of potential infection, and is being carried out in a safe and humane manner by fully trained APHA staff. Our response to this outbreak follows tried and tested procedures for dealing with avian flu outbreaks and we expect the cull to be completed later today.
It allayed fears food safety risk for consumers, adding the advice from the Chief Medical Officer and Public Health England remains that the risk to public health is very low.
Investigations are now ongoing to discover whether the outbreak is linked to cases found in Netherlands and Germany with further test results expected over the coming days.