A sweet shop owner in Pakistan has admitted killing 30 people, including children, by lacing confectionery with pesticides, according to local police.

Khalid Mehmood, 18, had allegedly wanted to take revenge on Tariq, his elder brother who co-owned the sweet shop.

Khalid told a court in central Punjab province: "I wanted to teach him a lesson. I was so angry that I mixed the pesticides bottle in the sweets being baked at that time", AFP reported.

The poisoned sweets were instead purchased by a local man who was celebrating the birth of his grandson, and gave the sweets to his friends and relatives.

Police said 52 people had consumed the sweets and 30 had died.

Among the dead were the baby's father, his aunt, six of his uncles and five children. Four people are currently in hospital and their condition is unknown.

Police initially suspected the incident to be accidental as a pesticide shop nearby was being renovated, with products left at the bakery for safe keeping.

Both the Mehmood brothers were arrested along with one of their employees. The brothers are due to appear in court again on Saturday.