Trump administration has announced that all domestic partners of foreign United Nations (UN) officials and diplomats will be denied US visas unless they are married. This is set to make the process more challenging for same-sex couples from countries where marriage equality remains illegal.

The policy, which reverses a 2009 decision by foreign secretary Hilary Clinton, came into effect on October 1 and according to Foreign Policy, it states that states that domestic partners of diplomats and UN officials who live outside of US territory must prove they are married in order to enter the country on a diplomatic visa.

“Same-sex spouses of U.S. diplomats now enjoy the same rights and benefits as opposite-sex spouses,” the U.S. mission wrote in a July 12 note to U.N.-based delegations. “Consistent with [State] Department policy, partners accompanying members of permanent missions or seeking to join the same must generally be married in order to be eligible” for a diplomatic visa.

Critics have argued that this new policy will create an undue hardship on foreign couples who reside in countries that criminalise same-sex marriage.

Former US ambassador Samantha Power denounced the policy on Twitter saying it is “needlessly cruel and bigoted.”

“State Dept. will no longer let same-sex domestic partners of UN employees get visas unless they are married,” she tweeted, noting that “only 12% of UN member states allow same-sex marriage.”

Needlessly cruel & bigoted: State Dept. will no longer let same-sex domestic partners of UN employees get visas unless they are married. But only 12% of UN member states allow same-sex marriage. https://t.co/MjZpRVLYcf

— Samantha Power (@SamanthaJPower) September 28, 2018

The conditions of this policy outline that partners of diplomats and UN officials posted in the US must show proof of marriage by December 31 or leave the country within 30 days.

“The Department of State will not issue a G-4 visa for same-sex domestic partners,” the U.N. human resources chief explained in a note distributed to staff last month. “As of 1 October 2018, same-sex domestic partners … seeking to join newly arrived U.N. officials must provide proof of marriage to eligible for a G-4 visa or to seek a change in such status.”

There are currently at least 10 UN employees in the United States who now need to get married by Dec. 31 in order to have their partners’ visas extended.