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An analytical theory of the quasi LP-modes in anisotropic optical fibres with a homogeneous circular core and homogeneous cladding is developed. Analytical expressions for the quasi LP-mode fields are obtained by the separated variable method and by the perturbation method under the following conditions. The Cartesian permittivity tensors of the core and cladding are diagonal and have the same orientation in the crosssection of the fibre. The longitudinal components of these permittivity tensors are equal, and the differences between the transversal and longitudinal components of these tensors are sufficiently small. The transversal components of the quasi LP-mode fields are derived from Maxwell's equations in the linear approximation on these differences. Solutions of the mode characteristic equation for the quasi LP-modes are reduced to the known solutions of the characteristic equation for the LP-modes in the isotropic optical fibre.