A porous refractory body, primarily a porous plug for the refractory lining of a vessel containing molten metal through which plug gas can be blown into the metal. This body has a cold crushing strength of not less than 200 kg/cm2 and consists of a coarse-grained refractory material with a minimum quantity of a suitable binding agent, and has permeable pores of a cross section not less than 0.05 mm and a gas permeability of at least 100, and preferably more than 500 nanoperm. The hot bending strength or modulus of rupture of the body at 1,400* C is from 20 - 60 kg/cm2. The refractory material is mixed with the binding agent, and the mixture is compressed with a pressure of at least 300 kg/cm2 before firing to bring substantially all of the grains into contact with adjacent grains.