Introduction.Explicit formulae or asymptotic formulae for Fourier coefficients of modular forms are useful tools for the study of several number-theoretic functions, for example, the number of representations of a natural number äs the sum of a fixed number of squares of integers or more generally, of an integral quadratic form by a positive definite integral quadratic form. From this standpoint, an estimate fl(7 1 ) = 0((detT) k " ( " + 1)/2 (mmT) 1 -k/2 ) was obtained in [24], following Kitaoka [12], for the Fourier coefficients a (T) of Siegel modular forms of degree n, half-integral weight k>2n, level s and having zero constant term in the Fourier expansions at all cusps, where min T is the "minimum" of the n-rowed positive definite half-integral matrix T.