Bangladeshi police have been alerted to check posts at the main entry points to the capital Dhaka to prevent the import of fruits which have been sprayed with alarming levels of a deadly chemical, officers said Monday.

After high levels of formalin, an illegal chemical which is sometimes used as a preservative and disinfectant, were found in almost all the fruits checked at Dhaka markets, the Dhaka Metropolitan Police (DMP) unveiled the move, DMP spokesman Masudur Rahman said.

"The check posts will be set up from June 11 at eight entry points of the city. Armed with formalin detection kits, our officers and magistrates will check every lorry carrying fruits to the capital," he said.

According to Agence France-Presse, anyone found to have carried formalin-laced fruits could be jailed for up to two years or fined up to 200,000 taka ($2,531), he said.

Fruits sold in Bangladesh contain an "alarming level of formalin" as an effort to extend their shelf life, repeated tests by laboratories and food inspectors have verified.

The "unprecedented" police move has been prompted by a massive outrage and a huge public outcry over formalin-mixed fruits.

Comparing the situation to an attempt at slow poison mass killing, Dhaka's police chief Benazir Ahmed pleaded with residents "not to get involved with buying, selling or consuming formalin contaminated fruits" on Sunday.

Fruits naturally contain 0.03-0.15 ppm (part per million) level of formalin. During the inspection, however, Dhaka's markets police found the level to range between 3.5 ppm to 46 ppm, Rahman said.

"It's an extremely dangerous situation. This level of formalin mixed in fruits can kill a lot of people," said Rahman.

A two-year-long test by a government health laboratory which discovered an unprecedented level of adulteration of other food items was also partly responsible for sparking police concern, according to AFP.

The Institute of Public Health (IPH) has conducted the test on 10,289 samples of 50 items and found that 47 items were adulterated, according to mass-circulated The Daily Star.

The items include edible oil, spices, sweets, milk products, lentils, pulses, juices, pickles, biscuits, jellies, dried fish, flours and tea leaves.