A United Nations official on countering torture has criticized a Turkish government decision to postpone his visit to the country saying the move "sends the wrong message."

U.N. Special Rapporteur on Torture Juan Mendez said Wednesday that Turkey delayed his four-day visit that would have started on Oct. 10.

Turkey declared a state of emergency after a failed coup on July 15 and began a massive crackdown on a movement led by U.S.-based Muslim cleric Fethullah Gulen, who it accuses of orchestrating the attempt.

Mendez said his visit would have been crucial in light of the thousands of arrests and the allegations of overcrowding and poor conditions in detention centers following the coup.

Mendez, whose term ends at the end of October, urged Turkey to allow his successor "unfettered access."