leaking kitchen tap under lever

[sohhiehwrd]

i have one of these in the kitchen Kitchen Mixer Tap, Monobloc, Swivel Spout, A (WT3002)
recently just under the lever it has started to leak any ides what it could be?if so how do i go about fixing it do i have to remove the whole tap?

 

[foxhole]

"O" ring has failed, you can replace or call a plumber who will replace tap.
Probably an allen key to remove grub screw that hold top of tap on giving access to main body and O rings.