A low NOx emission industrial burner comprising: - a hollow body (2, 5) defining a longitudinal axis, - a tubular element arranged within said hollow body at one open end thereof; - a diffuser arranged within said tubular element at a first end thereof inside the hollow body, so as to define a volume (26, 27) within said hollow body (2, 5); - a pipe for feeding comburent air into said volume (26, 27); - a combustible gas injection lance, arranged within said hollow body (2, 5) and connected to said diffuser; wherein said diffuser is provided with - first holes for injecting a first portion of combustible gas from said injection lance, into a first combustion zone provided within said tubular element and adjacent to said diffuser; - second holes for injecting a first portion of comburent air into said first combustion zone; - third holes for injecting a second portion of comburent air into a second combustion zone, provided within said tubular element, downstream of the first combustion zone and communicating with the latter, said second portion of comburent air crossing said first combustion zone; - a tube for injecting a second portion of combustible gas, from said injection lance, into a third combustion zone outside said tubular element, provided downstream of the second combustion zone and communicating with the latter, said second portion of combustible gas crossing said second combustion zone; the burner being further provided with a longitudinal passage, defined between the outer profile of said tubular element and the inner profile of said open end of the hollow body (2, 5) for injecting a third portion of comburent air into said third combustion zone, and wherein part of the second holes has a different inclination with respect to the remaining part of said second holes for injecting the first portion of comburent air into at least two primary combustion sub-zones within the same first combustion zone. - a hollow body (2, 5) defining a longitudinal axis, - a tubular element arranged within said hollow body at one open end thereof; - a diffuser arranged within said tubular element at a first end thereof inside the hollow body, so as to define a volume (26, 27) within said hollow body (2, 5); - a pipe for feeding comburent air into said volume (26, 27); - a combustible gas injection lance, arranged within said hollow body (2, 5) and connected to said diffuser; wherein said diffuser is provided with - first holes for injecting a first portion of combustible gas from said injection lance, into a first combustion zone provided within said tubular element and adjacent to said diffuser; - second holes for injecting a first portion of comburent air into said first combustion zone; - third holes for injecting a second portion of comburent air into a second combustion zone, provided within said tubular element, downstream of the first combustion zone and communicating with the latter, said second portion of comburent air crossing said first combustion zone; - a tube for injecting a second portion of combustible gas, from said injection lance, into a third combustion zone outside said tubular element, provided downstream of the second combustion zone and communicating with the latter, said second portion of combustible gas crossing said second combustion zone; the burner being further provided with a longitudinal passage, defined between the outer profile of said tubular element and the inner profile of said open end of the hollow body (2, 5) for injecting a third portion of comburent air into said third combustion zone, and wherein part of the second holes has a different inclination with respect to the remaining part of said second holes for injecting the first portion of comburent air into at least two primary combustion sub-zones within the same first combustion zone. - first holes for injecting a first portion of combustible gas from said injection lance, into a first combustion zone provided within said tubular element and adjacent to said diffuser; - second holes for injecting a first portion of comburent air into said first combustion zone; - third holes for injecting a second portion of comburent air into a second combustion zone, provided within said tubular element, downstream of the first combustion zone and communicating with the latter, said second portion of comburent air crossing said first combustion zone; - a tube for injecting a second portion of combustible gas, from said injection lance, into a third combustion zone outside said tubular element, provided downstream of the second combustion zone and communicating with the latter, said second portion of combustible gas crossing said second combustion zone; the burner being further provided with a longitudinal passage, defined between the outer profile of said tubular element and the inner profile of said open end of the hollow body (2, 5) for injecting a third portion of comburent air into said third combustion zone, and wherein part of the second holes has a different inclination with respect to the remaining part of said second holes for injecting the first portion of comburent air into at least two primary combustion sub-zones within the same first combustion zone.