South Korean prosecutors sought a one-year jail term for the owner of a Michelin-starred restaurant accused of using ants as a dessert garnish, local media reported.

Ants are not among the 10 insect species approved for human consumption under the country's laws. The approved list includes grasshoppers, locusts and two-spotted crickets, among others.

Prosecutors on Monday also asked that the restaurant, which holds two Michelin stars, be fined 20 million Korean won ($13,510; £10,100).

The owner admitted to serving ants but argued that they were used in a "small part" of the restaurant's 15-course menu – as a topping for sorbets – and that diners were told they could opt for non-ant toppings.

The case came to light after officials from the Ministry of Food and Drug Safety found reviews that diners had posted online with photographs of dishes sprinkled with ants.

Investigators estimate that some 49,000 ants, imported from the US and Thailand, were used in several dishes over four years.

Health authorities also found that the restaurant used ants that "contained up to 55 times more heavy metals than typical edible insects", according to a report on The Chosun Daily.

South Korean authorities consider several criteria in deciding whether insects can be approved as food. These include food safety risks, toxicity, nutritional value, and whether they can be bred and processed hygienically.

In its defence the restaurant owner argued that just 60% of diners had opted to try the ants, while the rest were served alternatives like fermented vinegar and edible flowers.

He added that restaurants in other countries, such as Australia, Denmark and the UK, also use ants as ingredients.

Court documents did not name the restaurant nor its owner. Ten restaurants in South Korea, all located in capital city Seoul, have been awarded two Michelin stars.

The Michelin Guide awards up to three stars to eateries based on ingredient quality, flavour mastery, cooking technique, chef's personality and consistency.

Two stars denote restaurants that do "excellent cooking" and are "worth a detour", according to Michelin's criteria.

The court is set to deliver its verdict on September 2.

Ants are eaten, sometimes even valued as a delicacy, in several Asian, African and Latin American cultures. Weaver ants and their eggs are used in Thai and Cambodian cooking, while in Colombia, queen ants are as prized as caviar.