A Christian registrar who refused to perform same-sex civil partnership unions because she believes that gay marriage is "sinful" has won her claim for discrimination, testing the boundaries of the fledgling religious discrimination law.

"I am delighted at this decision," Ms Ladele said. "It is a victory for religious liberty, not just for myself but for others in a similar position. Gay rights should not be used as an excuse to bully and harass people over their religious beliefs."

The case was financed by the Christian Institute, a charity that has also filed a lawsuit against the internet seach engine Google for blocking an anti-abortion online advertisement.

Mike Judge, the institute's head of communications, said: "This important ruling confirms that gay rights should not be treated as trumping religious rights. The law clearly recognises this. If we really believe in equality before the law, that means respecting people who have sincerely held religious beliefs on sexual ethics. The witch-hunt against those who disagree with homosexual practice has to stop."