Dutch officials have detected a second case of bird flu on a southern Netherlands farm, officials said Thursday, but could not yet say whether the strain was of a highly contagious variety discovered earlier this week.

The latest outbreak was detected in three barns containing 43,000 chickens on a farm at Ter Aar, just east of The Hague, the Dutch food and safety watchdog NVWA said.

The outbreak was of the H5 strain, but "it is not clear whether it was of the highly pathogenic variety or not," added the Dutch economic affairs ministry in a letter sent to parliament on Thursday.

"The earliest results are expected by the end of tomorrow (Friday)," it said.

The powerful Dutch poultry industry has now been paralysed for a second time this week with a nationwide ban on the transport of all poultry and related products since 2:00 pm (1300 GMT) on Thursday.

The ban will last up to 72 hours.

Authorities have also thrown a 10 kilometre (6.2 mile) cordon around the farm, with four other farms also being tested for avian influenza.

The chickens are being destroyed and the farm disinfected, the NVWA added.

The European Commission said it was in "constant contact" with Dutch authorities and was ready to take further action once test results from the birds were through.

Dutch officials initially 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 on the virus in Britain and Germany.

Some 150,000 birds were destroyed at the farm in Hekendorp, which lies about 25 kilometres southeast of Ter Aar.

Officials have identified the flu as being the 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.

But Dutch authorities have said human infection can only occur following "intense and direct contact" with infected birds.

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 95 million chickens kept on Dutch poultry farms and egg exports totalled some 10.6 billion euros ($13.2 billion) in 2011, according to the latest Dutch statistics.

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