Dutch officials said bird flu had been found at another poultry farm in the Netherlands, the fourth in recent weeks.

The Economics Ministry said the farm's 28,000 birds were being destroyed.

It said the flu infection was of the same H5 variety found at farms across Europe and Asia in recent months.

It was not yet clear how infectious the strain was, the ministry said.

A ban on transporting poultry products has been imposed and the four other farms within that radius are being inspected for signs of bird flu, the ministry said.