Birmingham: Former South Africa spinner Paul Adams has questioned New Zealand skipper Kane Williamson's integrity after he did not walk out despite being caught behind by wicketkeeper Quinton de Kock.

Williamson struck a composed unbeaten century to help New Zealand post a four-wicket win over South Africa in a World Cup game here Wednesday. However, his knock was marred by a controversy after he was caught-behind by Kock in the 38th over off the bowling of leg-spinner Imran Tahir. Williamson was at 76 then.