Mere seconds after the earthquake alert sounded, Ms Regina Hong felt the whole house starting to shake violently.

The 25-year-old Singaporean, who works as a translator in Takikawa city, about 90km away from Sapporo, said: "We were woken up at around 3am and had to shield our heads as the whole house was shaking."

Ms Hong has lived in Takikawa for about a year with her Singaporean husband, who is a high school English teacher.

"My dish-drying rack fell off and some of my plates shattered. We had to use the torchlight to navigate our way through the house," she told The Straits Times.

Ms Hong soon got over the initial shock and started lending a hand. Hours later, she was helping the local authorities translate crucial information, such as where to get water supplies, into English and Chinese to help people who do not understand Japanese.

She was one of the Singaporeans who felt the magnitude-6.7 earthquake which hit Japan's northernmost prefecture of Hokkaido yesterday morning.

The Ministry of Foreign Affairs said there are no reports of injuries or casualties involving Singaporeans.

Madam Long Shiau Wee, 54, said it was the first time she had experienced an earthquake in Hokkaido, where she has lived for the past eight years.

"I wasn't too worried because I know the buildings are earthquake-proof," said the Singaporean, who is chief executive of Niseko Village, a two-hour drive from Chitose Airport.

Her immediate concern was for the guests. There are two hotels with a total of about 700 rooms in Niseko Village.

"It is not too chaotic here, but the guests are quite anxious. Thankfully, basic needs such as water and the mobile Internet are not affected, and we are still able to provide food for guests for now."

Travel agencies in Singapore said they have been in touch with customers affected by the quake.

Chan Brothers said several tourist groups in Hokkaido experienced power and water supply disruption. But all the members are safe and have contacted their families.

"For two of the groups, we have also made the necessary changes... which include replacing some of the affected attractions with alternatives," said agency spokesman Justine Koh.

Dynasty Travel does not have any tour groups going to Hokkaido until later this month. It said it will monitor the situation.