In this paper we present a method to estimate forces and moments applied to a robotic chain, which is based on the recursive Newton-Euler algorithm. The method uses a six axis force/torque (F/T) sensor, located at the base of the kinematic chain, together with a tactile sensor network, which covers most of the surface of the robot. The tactile sensors measure the contact locations, whereas the F/T sensor measures the magnitude and the direction of the contact forces. We show that the number of contacts that is possible to estimate reliably is strictly dependent on the amount of information retrieved from the sensors. When this critical number is exceeded, infinite solutions satisfy the estimation problem, though, in some cases we can choose one of the possible solutions and draw the probability distribution of its error.