Criticize, the word is criticize.
Sorry but it's "criticise."
The rule I follow (and too many people don't) is to paste the headline without any changes. The article is from a British paper which (surprise!) uses British spelling.
Criticize those who change headlines, not those of us who follow rules.
The spelling used is the UK spelling---which I was taught as well. (and "-our" when used with Neighbour, Harbour, endeavour, etc...used to drive my Div-O nuts!)
It is not considered incorrect.