Story highlights A law in Canberra, Australia, allowing same-sex marriage is declared invalid

A court says a federal act, which doesn't permit same-sex marriage, takes precedence

Activists say the decision is "devastating" for the couples who got married

They vow to lobby the national parliament to change federal legislation

For five days, same-sex couples could get married in Australia's capital city of Canberra. Those who did were the first in the country to do so.

But that fleeting window was slammed shut Thursday by the Australian High Court, which ruled that a recent local law legalizing same-sex marriage was invalid.

That means that the marriages of the couples who took advantage of the law to tie the knot -- 27 according to local media -- will be annulled.

"This is devastating for those couples who married this week and for their families," said Rodney Croome, the national director of the advocacy group Australian Marriage Equality. "However, this is just a temporary defeat."

The Australian court's decision is the latest setback for gay rights in the Asia-Pacific region. On Wednesday, India's top court ruled that sex between consenting homosexual partners is illegal in the country, prompting dismay from human rights groups.

Australian gay rights activists said their fight would now shift to lobbying the national parliament to change federal legislation.

The high court said Thursday that the federal Marriage Act, which doesn't permit same-sex marriage, takes precedence over the law passed by the legislative assembly in Canberra, also known as the Australian Capital Territory.

The lawmakers in the ACT, which has a population of about 380,000 people, would have been aware that their same-sex marriage law wouldn't be allowed to override federal law.

But their move has succeeded in fostering renewed debate on the issue in Australia.

The activists' goal of changing the federal Marriage Act appears to be a stern challenge, though. Prime Minister Tony Abbott and his conservative coalition oppose same-sex marriage.

That's despite public pressure from his family.

"Sad news that the ACT same-sex marriage law has been overturned," tweeted Abbott's lesbian sister, Christine Forster.

"Focus now firmly on federal parliament," wrote Forster, who is a lcouncil member in Sydney.