What wire to use to extend omlopp ikea lights

I have some omlopp from Ikea drawer lights and the correct transformers, but unfortunately the cable on the lights is pretty short and needs extending for quite a few.

I'm happy enough to break into the wires and extend them (as they have little Molex style connectors on the end that I can't find, there is another dead question here trying to do the same) but I just need to know the correct wire to use.

The LED lights are 24V, 2W each:

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A link to something I could use on Maplin or screwfix would be great.