Thousands marched through central Seoul yesterday in what organisers described as South Korea's biggest annual gay pride parade, with many celebrating the US Supreme Court's historic decision allowing same-sex couples nationwide to wed. On the other side of police barriers around Seoul Plaza, thousands of Christian activists waved banners and chanted slogans at those taking part, condemning what they called an attempt to turn the city into "Sodom and Gomorrah". Some held up banners reading "Hell is upon you! Repent!" towards the marchers, who responded by cheering and waving rainbow flags at them. Police estimated more than 6,000 people took part in the hour-long parade in the heart of the capital to mark the finale of the annual Korea Queer Festival that started on June 9. Organisers estimated the number of participants - gay, lesbian and bisexual and transgender people - at more than 20,000, which they described as the largest turnout for the event. Homosexuality is not illegal in South Korea. But gay and transgender people live largely under the radar in a country that remains deeply conservative about matters of sexual identity and where many still regard homosexuality as a foreign phenomenon. Gay rights activists say some progress has been made in recent years, and Friday's US Supreme Court decision cheered those taking part in the event. Many held rainbow-coloured banners reading: "Some people are gay. That's okay." The court ruled on Friday that gay marriage is a legal right in all 50 states, a decision praised by President Barack Obama as "a victory for America". "What happened in the US was incredible... I hope that I and my girlfriend will be able to celebrate the same here one day," said Suzy Lee. "But we know it will take many, many years here in the South." The annual parade - which began in 2000 - has in recent years attracted a growing number of participants, as well as increasing opposition from conservative Christian groups. Previous parades were often marred by angry protests by Christians, who threw water bottles at marchers and tried to block their route by lying down in the street. Concerns over public safety and potential clashes prompted police to ban the planned parade last month. A Seoul court later overturned the ban.