Australia’s High Court has overturned legislation allowing same-sex marriages in the Australian Capital Territory (ACT).

The ACT Parliament passed a bill in October making the territory the first part of Australia to legalise equal marriage.

But the Federal Government challenged the decision, saying it was inconsistent with federal laws.

Some 27 couples who married since the law came into effect last weekend will now have their unions declared invalid.

The court said the issue should be decided by the Australian Federal Parliament – which in September 2012 voted down equal marriage legislation.

Australian Marriage Equality National Director Rodney Croome said in a statement: “This is devastating for those couples who married this week and for their families.”

Ivan Hinton, who had married his partner Chris Teoh on Saturday, tearfully told reporters: “In less than a week we’ve been married and we’ve been unmarried, at least on a legal level.”

“We’re still married,” he added. “I’ve made commitments to Chris to spend the rest of my life with him.”

Although the ACT legislation came into effect in October this year, Prime Minister Tony Abbott warned anyone planning to marry to wait until the constitutional challenge against the law is resolved.

Despite having a gay siblingAustralia’s Prime Minister Tony Abbott continues to oppose equal marriage and has supported efforts to halt the ACT’s equal marriage bill in the courts.

Same-sex couples living in the ACT have been allowed to register their partnerships since 2008 and hold civil partnership ceremonies since 2009, when the ACT became the first territory in Australia to introduce such legislation.

Australian federal law was amended in 2004 to specify that marriage can only be between a man and a woman. But it also specifically applied to heterosexual couples, and some lawyers argue that leaves states free to legislate for same-sex marriage.

Equal marriage remains banned at a federal level in Australia.