The brick pagoda located at Kaiyuan temple in Dingzhou city in North China's Hebei province. [Photo/Chinanews.com]

Renovation of China's highest brick pagoda in China, which has been ongoing for the last three decades, is near completion, authorities said on Thursday.

The pagoda, located at Kaiyuan temple in Dingzhou city in North China's Hebei province, is the highest existing brick tower in the country. Dating back 936 years, the towering brick-and-wooden structure stands at 83.7 meters tall.

It was damaged in an earthquake in 1884, but renovation did not start until a century later because of difficulty finding materials and recreating old techniques, said Chen Junfeng, a renovation expert working on the project.

"The pagoda is disproportionate and imbalanced, because there are more than a dozen types of bricks, with each accepting a different amount of force. Therefore, it can not be reinforced using cement," said Chen.

The top of the pagoda leans toward the southwest in summer and northwest in winter due to wind.

The renovators built another layer of brick and tile outside the pagoda and used a steel structure to connect to the old bricks.

"We could only let time to solve the problem. When we completed each storey, we let the structure to sink in and bond for a period of time before continuing work," said An Yafei, director of the cultural relic conservation of the pagoda.

An said the exterior of the pagoda has been renovated and experts are putting the finishing touches on the tower.