A running club on Wednesday admitted leaving a trail of flour in a Singapore metro station which prompted a security scare and a three-hour shutdown of the station.
In a statement the Seletar Hash House Harriers, an all-male group that describes itself as a "drinking group with a running problem", apologised for the "alarm and inconvenience" caused to the public.
Three members had sprinkled flour at several points in the underground Woodleigh MRT station, the statement said, adding that it was the safest way to cross a busy road in the suburban Serangoon district.
But the sight of white powder sparked security fears, which saw police and hazardous materials units respond.
The station was shut for three hours while officers in protective suits searched the station before it was determined that the white substance was flour.
"Upon learning of the subsequent investigations at Woodleigh station, our three members stepped forward immediately to identify themselves and have cooperated fully with the authorities," the statement added.
"They are sorry that their actions caused public alarm and inconvenience."
One of the group's members, a 69-year-old man, was arrested for causing public alarm while two others, aged 59 and 70, are helping police with investigations.
The Seletar Harriers is a chapter of a loose worldwide federation of "Hash House Harriers", a running group set up by beer-loving British colonial expatriates in what was then Malaya in 1938.
"Hares" are given the task of marking a trail to direct runners, usually using flour or chalk.