Senate Speaker Pornpetch Wichitcholchai has maintained that senators appointing their relatives to work on their Senate teams is not illegal.
Mr Pornpetch made his remarks on Monday in response to criticisms after the Internet Dialogue on Law Reform (iLaw) disclosed that more than 50 cousins of senators have filled seats in several Senate working panels.
The critics questioned the suitability of the appointments which are viewed as nepotism.
Mr Pornpetch, however, came out in the senators' defence, saying certain positions in public office may require someone, who the senators can trust, to fill. The Senate speaker downplayed concern the issue could be investigated by the House Committee on corruption and misconduct.
Mr Pornpetch said if hiring cousins broke no law, it would also not violate moral ethics either. He said the issue is permissible under relevant regulations.
Mr Pornpetch added such regulations have been in place well before he became Senate speaker.
Meanwhile, Thai Sang Thai Party's Treerat Sirichantaropas, in his capacity as secretary of the House committee on corruption and misconduct, said he will ask the House committee to probe the matter.