Utah’s Republican governor on Saturday signed a bill that bans young people who are transgender from receiving gender-affirming healthcare as other states consider similar legislation.

The governor, Spencer Cox, who had not taken a public position on the transgender care measure, signed it a day after the state legislature sent it to his desk. Utah’s measure prohibits transgender surgery for young people and disallows hormone treatments for minors who have not yet been diagnosed with gender dysphoria.

Republicans controlling Utah’s legislature made the ban a priority and weighed a first draft of the measure less than two days after the state’s lawmakers opened this year’s legislative session on 17 January.

Cox’s signing of the bill comes as lawmakers in at least 18 states consider similar legislation taking aim at young transgender people’s healthcare.

In a statement, Cox said that he based his decision to sign the bill on a belief that the safest thing to do was halt “these permanent and life-altering treatments for new patients until more and better research can help determine the long-term consequences”.

He added: “While we understand our words will be of little comfort to those who disagree with us, we sincerely hope that we can treat our transgender families with more love and respect as we work to better understand the science and consequences behind these procedures.”

Utah’s chapter of the American Civil Liberties Union stood among the organizations who had urged Cox to veto the bill, admonishing him in a letter about “the damaging and potentially catastrophic effects this law will have on people’s lives and medical care and the grave violations of people’s constitutional rights it will cause”.

The ACLU’s letter continued: “By cutting off medical treatment supported by every major medical association in the United States, the bill compromises the health and wellbeing of adolescents with gender dysphoria.

“It ties the hands of doctors and parents by restricting access to the only evidence-based treatment available for this serious medical condition and impedes their ability to fulfill their professional obligations.”

Sponsoring the bill Cox signed was a Republican state senator named Mike Kennedy, who works as a family doctor and has argued that it is right for the government to oversee healthcare policies pertaining to gender and young people.

The Associated Press contributed reporting