Police officers investigate around Ninomaru Palace, a national treasure, at Nijo Castle in Kyoto on April 18, 2017. (Kyodo photo)

KYOTO: Three Taiwanese women have been arrested on suspicion of entering Nijo Castle, a Unesco World Heritage site in Kyoto, with the aim of blotting it with powder in April 2017, police said on Thursday.

The women, ranging in age from 41 to 57, admitted to the allegation, saying they “sprinkled incense powder (at the castle) to purify the souls of the deceased.”

They emerged as suspects shortly after the incident on April 18, 2017, when the three visited the castle along with family members.

The brown powder was found at 54 locations at the castle, including the inside of the Ninomaru Palace, a national treasure, forcing the popular tourist spot to be temporarily closed for an inspection by the local government.

The women, who left Japan after the incident, re-entered Japan on Wednesday night when they arrived at Narita airport near Tokyo, and were taken into custody by Kyoto police.

They were in possession of powder weighing 1.2 kilogrammes, similar to the one scattered at the castle a year ago, at the time of their arrest, according to the police. The purpose of their visit is believed to be sightseeing.

In February 2015, Ninomaru Palace was vandalised with an oily liquid.

The castle was originally built in 1603 as the official residence of the first Tokugawa Shogun Ieyasu.