Résumé
A strong edge-colouring of a graph is a proper edge-colouring where each colour class induces a matching. It is known that every planar graph with maximum degree$\Delta$has a strong edge-colouring with at most$4\Delta+4$colours. We show that$3\Delta+1$colours suffice if the graph has girth 6, and$4\Delta$colours suffice if$\Delta\geq 7$or the girth is at least 5. In the last part of the paper, we raise some questions related to a long-standing conjecture of Vizing on proper edge-colouring of planar graphs.