A teenage girl banned from wearing a chastity ring in class lost a legal challenge against her former school at Britain's High Court Monday.

Lydia Playfoot, 16, had argued that the ban at the Millais School in Horsham, about 40 miles south of London, was an "unlawful interference" with her right to express her Christian faith.

But deputy High Court judge Michael Supperstone disagreed with her and supported her school's contention that the ring was not an integral part of the Christian faith.

Playfoot wears a ring as a sign of her commitment to abstinence from sex until marriage. Many Christian teenagers worldwide wear the chastity rings, which were inspired by "The Silver Ring Thing," an abstinence program launched in the United States in 1996.

The ruling "will mean that slowly, over time, people such as school governors, employers, political organizations and others will be allowed to stop Christians from publicly expressing and practicing their faith," Playfoot said in a statement.

The school had said the ring fell outside its uniform policy, which makes exceptions for Muslims wearing head scarves and Sikhs wearing steel bracelets.

Her lawyer Paul Diamond had told the court that secular authorities, including school authorities, "lack capacity to rule on the correct manifestation of religious belief" and the ban contravened Playfoot's right to religious expression.

Playfoot said she was considering an appeal.