Dutch officials have detected bird flu on three more farms, but cannot yet say if the strains are a highly contagious variety discovered earlier this week.
The Dutch economic affairs ministry also confirmed that a second bird flu outbreak, detected yesterday on a farm close to the first case east of The Hague, was the highly pathogenic H5N8 strain, previously detected only in Asia.
Some strains of avian influenza are fatal for chickens, and pose a health threat to humans, who can fall sick after handling infected poultry.
Dutch authorities have said human infection can only occur following "intense and direct contact" with infected birds.
The latest outbreak was first reported on a small farm in Kamperveen, around 100km north of the first outbreaks, the economic affairs ministry said in a statement.
"The bird flu virus has been detected on a farm with around 10,000 chickens," it said.
Later the ministry added that bird flu symptoms had also been detected on two other farms less than one kilometre from the farm in Kamperveen.
The birds on all three farms will be destroyed and the farms disinfected, the ministry said, with tests being carried out to establish if the strain is H5N8.
Dutch officials on Sunday banned the transport of poultry around the Netherlands after the discovery of a highly infectuous strain of bird flu following outbreaks of similar strains of the virus in Britain and Germany.
Some 150,000 birds were destroyed at the farm where the initial outbreak was detected.
The H5N1 strain of bird flu has killed more than 400 people, mainly in southeast Asia, since first appearing in 2003.
Another strain of bird flu, H7N9, has claimed more than 170 lives since emerging in 2013.
The H7N7 strain of avian flu severely hit the Netherlands in 2003 with health authorities destroying some 30 million birds in an effort to quash an outbreak.
There are some 95m chickens on Dutch poultry farms and egg exports totalled some €10.6bn in 2011, according to the latest Dutch statistics.
