A sterilisation apparatus for sterilising a channel of a surgical scoping device, the apparatus comprising: a gas supply, a sterilisation instrument configured to be inserted through the channel of a surgical scoping device, the sterilisation instrument comprising: an elongate probe comprising: a transmission line for conveying radiofrequency electromagnetic energy and/or microwave EM energy, and a probe tip connected at the distal end of the transmission line for receiving the RF and/or microwave EM energy, the probe tip comprising an electrode assembly configured to produce an electric field from the received RF and/or microwave frequency EM energy to generate a plasma of the ionisable gas delivered to the channel from the gas supply, characterised in that: the gas supply has a conduit to deliver an ionisable gas to the channel of the surgical scoping device, and in that the sterilisation instrument is separate from the gas supply and the conduit, and in that the sterilization instrument is free of a conduit for conveying ionisable gas for generation of a plasma by the electrode assembly. apparatus comprising: a gas supply, a sterilisation instrument configured to be inserted through the channel of a surgical scoping device, the sterilisation instrument comprising: a gas supply, a sterilisation instrument configured to be inserted through the channel of a surgical scoping device, the sterilisation instrument comprising: an elongate probe comprising: a transmission line for conveying radiofrequency electromagnetic energy and/or microwave EM energy, and a probe tip connected at the distal end of the transmission line for receiving the RF and/or microwave EM energy, the probe tip comprising an electrode assembly configured to produce an electric field from the received RF and/or microwave frequency EM energy to generate a plasma of the ionisable gas delivered to the channel from the gas supply, characterised in that: the gas supply has a conduit to deliver an ionisable gas to the channel of the surgical scoping device, and in that the sterilisation instrument is separate from the gas supply and the conduit, and in that the sterilization instrument is free of a conduit for conveying ionisable gas for generation of a plasma by the electrode assembly. a transmission line for conveying radiofrequency electromagnetic energy and/or microwave EM energy, and a probe tip connected at the distal end of the transmission line for receiving the RF and/or microwave EM energy, the probe tip comprising an electrode assembly configured to produce an electric field from the received RF and/or microwave frequency EM energy to generate a plasma of the ionisable gas delivered to the channel from the gas supply, characterised in that: the gas supply has a conduit to deliver an ionisable gas to the channel of the surgical scoping device, and in that the sterilisation instrument is separate from the gas supply and the conduit, and in that the sterilization instrument is free of a conduit for conveying ionisable gas for generation of a plasma by the electrode assembly. the gas supply has a conduit to deliver an ionisable gas to the channel of the surgical scoping device, and in that the sterilisation instrument is separate from the gas supply and the conduit, and in that the sterilization instrument is free of a conduit for conveying ionisable gas for generation of a plasma by the electrode assembly.