Animal rights campaigners believe the fire at Christchurch's Tegel chicken factory will increase the suffering of poultry.

Fire Safety Officers are back at the wrecked building today, looking for the cause of Thursday's blaze.

SAFE campaign director Hans Kriek says chickens are produced continually to feed the plant. He says any delay in their slaughter means the birds keep on growing, and can end up too heavy for their own legs.

Hans Kriek says chickens sometimes starve to death on farms because they become too heavy to walk to their food.

Mr Kriek says he understands one of Tegel's competitors is helping with the slaughtering, but he is concerned they will not be able to keep up with the number of chickens.