A street dog has melted hearts online after apparently imitating customers at a food stall and offering a leaf as payment.

A vendor selling grilled skewers said the dog watched customers hand over money for food. After observing several transactions, the dog disappeared briefly and returned with a small leaf in its mouth.

"This dog was sitting watching the customers who took food from me and gave me a currency note in exchange," the vendor said. "After a while, he immediately got up and brought a piece of leaf, and looked at me with innocent and hopeful eyes."

Moved by the dog's attempt to join in the exchange, the vendor rewarded it with food. The clip has joined the week's roundup of wholesome viral stories.

Behavioural scientists note that dogs are keen observers of human routines, and the animal's imitation of the exchange ritual is a striking example of social learning in action.

The story joins other feel-good animal moments this week, including the first California sea-turtle nesting and the United Nations' landmark sea-level declaration protecting island nations, both covered in weekly good-news roundups.