BEIJING (AP) — Chinese authorities have ruled out arson as the cause of a fire that damaged a 1,300-year-old monastery that is considered the spiritual heart of Tibetan Buddhism.

Saturday's fire at the Jokhang in the center of the Tibetan capital, Lhasa, burned an area of about 50 square meters (538 square feet), the official Xinhua News Agency said.

The fire was quickly extinguished and all 6,510 registered cultural relics remained intact, including a famed life-size statue of the Buddha when he was 12 years old. No injuries were reported from the blaze and the monastery reopened the next day.

The cause of the fire, which broke out in a ventilating chamber, was being investigated, though arson was ruled out, Xinhua said in its report Wednesday.

Although the main structure was not damaged, Xinhua said workers had removed the monastery's golden cupola to guard against any collapse and had added protective supports around the Buddha statue known as the Sakyamuni Jowo.

The fire occurred when many Tibetans were celebrating Losar, the New Year festival that began Friday. Video on Chinese social media showed a roof in the monastery complex hit by large flames that were visible from hundreds of meters (yards) away.

The sprawling temple complex is a UNESCO World Heritage Site that houses sacred scriptures as well as relics and is a main center for learning in the Tibetan, or Tantric, Buddhist tradition. Located in Lhasa's central Barkhor square, it draws pilgrims who circle the complex praying on hands and knees to seek blessings.

Like other sites of Buddhist learning in Tibet, it is tightly controlled by Chinese communist authorities, who have ruled the Himalayan region with an iron fist since their troops arrived in 1951.

Pledges to allow considerable autonomy were jettisoned after a 1959 uprising during which the Dalai Lama, Tibet's Buddhist leader, fled to India where he continues to reside.

Thousands of sacred Tibetan Buddhist sites were heavily damaged during the 1966-76 Cultural Revolution, although many have since been rebuilt and opened to visitors, including Lhasa's famed Potala Palace.