Six works of art at a Dutch national museum may have been created by famed ukiyo-e artist Katsushika Hokusai, a researcher at the museum says.

Five of the Edo Period artworks are paintings that used Western-style watercolor techniques and are believed to have been influenced by German physician Philipp Franz von Siebold (1796-1866), whom Hokusai (1760-1849) was acquainted with, according to the Museum Volkenkunde in Leiden.

The remaining artwork is a woodblock print of Edo, now known as Tokyo.

Some Japanese experts, however, say the artworks must be carefully scrutinized since almost none of the traits known to exist in the woodblock master’s other works were found in the Dutch pieces.

“Judging from the image, the lines and the shapes of the objects don’t have Hokusai’s characteristics,” said Shugo Asano, an ukiyo-e researcher who heads the Museum Yamato Bunkakan in Nara Prefecture. “Careful research would be needed to judge whether they are the works of Hokusai.”

The Dutch museum’s view was reported by researcher Matthi Forrer on Saturday at the 10th International Siebold Collection Working Conference in the city of Nagasaki.

The five paintings depict townscapes from Edo. These include a river, bridge and Mount Fuji on Japanese traditional paper measuring about 40 cm by 30 cm.

The Dutch museum owns a collection of artworks Siebold brought from Japan. Two years ago, a list of his collection written by him was discovered.

Upon viewing the list, Forrer found a description of the six artworks that said the paintings were done by Hokusai using a Western-style technique.

Since the description contained detailed information about the pieces, Forrer believes they were likely painted by Hokusai.

Siebold arrived in Nagasaki in 1823 as a physician along with a mission from his country. He is believed to have met Hokusai when he visited Edo.

Forrer said Hokusai may have painted the watercolors to show that he could paint as well as Western artists, later giving them to Siebold.