Residents were baffled as government officials released geese to clean up a moat in northern Thailand.

Locals were puzzled when the raft of fowl was found paddling in the previously empty city canal in Chiang Mai province on August 21.

Footage shows the geese grazing on the banks as people posed for photos next to them. More were seen drifting in the middle of the algae-stained water.

The birds were allowed to roam freely, but caused traffic chaos when they wandered in front of cars on the busy road nearby. At night, they were corralled into a bamboo enclosure at one end of the moat.

Authorities said the geese were part of a 10-day pilot project to 'naturally' eliminate duckweed and improve water quality in the murky green moat.

However, several residents questioned the effectiveness of the 'environmentally friendly' approach, saying it caused more trouble than good.

Passerby Oil Kanyaporn said: 'Upon returning to Chiang Mai and heading home, I passed the moat near Kad Pratu Chiang Mai and saw the flock swimming around. Someone was throwing rocks at them, while another was trying to catch them.

'When I approached, the man told me he was a municipal official who was herding the geese into a pen set up by the moat. There were 10 geese, and they were chasing each other in a chaotic mess. At one point, they waddled onto the road and oncoming cars barely avoided them. People in the area were panicking, fearing the geese might get hit by a car.

'I felt sorry for the geese and for the municipal officials struggling to herd them back into the pen. Releasing them around the moat without barriers is dangerous. Without proper space or protection, they could easily be hit by cars.'

Former mayoral city candidate Teerawuth Kaewfong said the geese could also exacerbate water pollution as their droppings serve as fertiliser allowing green algae to flourish in the moat.

He said: 'Goose manure is fertiliser, adding nitrogen and phosphorus to the polluted water. If geese walk onto the roads, they become a traffic hazard causing suffering for both the animals and humans.

'Solving the wastewater problem must begin with treating water from markets and communities, not relying on geese. What Chiang Mai needs is not geese swimming in the moat, but a serious and sustainable wastewater treatment policy.'