More than 100 Customs officers are learning Thai in the wake of allegations that women from Thailand are being targeted at the airport as suspected prostitutes.
But the Immigration Department - at the centre of the claims - has rejected an offer from the Thai Consulate to give its officers language and culture classes.
Thai Consul-General Rathakit Manathat said he had discussed the treatment of Thai visitors and raised the idea with heads of both departments.
Customs chief John Tsang Chun-wah had agreed to the offer while Immigration Director Ambrose Lee Siu-kwong had indicated a similar course was already available for officers, he said.
Mr Rathakit said he was not disappointed by the Immigration Department's response and told Mr Lee the consulate was always ready to assist.
An immigration spokesman said 11 officers attended a Thai-language course last year.