Recent experiments revealed the existence of an attractive force of like charges on water droplets in oil (Nikolaides et al., Nature 2002). It is known that a charged particle trapped at a liquid interface exerts a non-uniform electric stress that results in a deformation of the surrounding interface; the superposition of such one-particle dimples induces a capillary repulsion. Here we show that the electric stress comprises additional two-particle contributions that lead to a much stronger attractive force and could well be at the origin of the mentioned experimental findings.