An electrosurgical resection instrument 300 having an instrument tip that comprises an energy delivery structure capable of emitting both localised radiofrequency (RF) electromagnetic (EM) energy and microwave EM energy into biological tissue, wherein the device comprises a fluid feed conduit 296 for delivering fluid to the instrument tip. The device further includes a coaxial feed cable and first and second conductor elements 284, 286. The elements 284, 296 are arranged to act as active and return electrodes to convey RF RM radiation to act as active and return electrodes to convey RF EM radiation corresponding to the RF signal., and as antenna to radiate microwave EM radiation corresponding to the microwave signal. The fluid may be a saline liquid, gas, or plasma. The device is able to cut and perform haemostasis i.e. seal broken blood vessels. In another aspect the first and second conductive layers 348,350 (Fig 12) are set back from the edges of the planar body except at an RF cutting portion located along one or both sides edges and/or the distal end of the planer body.
