The public prosecutor's decision to drop five charges against construction tycoon Premchai Karnasuta has been met with fierce criticism.

Social media has been flooded with angry questions after the Office of Public Prosecution Region 7 announced its decision on Wednesday to drop almost half of the charges against Mr Premchai.

The president of Italian-Thai Development and three of his friends were arrested on Feb 4 and charged with poaching in the Thungyai Nareusuan Wildlife Sanctuary, a Unesco World Heritage site, in Kanchanaburi province.

Somsri Wattanapaisarn, director-general of the regional public prosecution office, read out the prosecution office's decision.

Prosecutors will press on with six charges against Mr Premchai. These are carrying firearms in public without permission, colluding to hunt wildlife in a wildlife sanctuary without permission, hunting protected wildlife without permission, possessing protected wildlife carcasses without permission, concealing wildlife carcasses obtained illegally and collecting wildlife items in a national forest reserve without permission

The five charges dropped were entering a wildlife sanctuary without permission, possessing wildlife-hunting tools, attempting to hunt wildlife in a wildlife sanctuary without permission, committing cruelty to animals and possessing firearms and ammunition without permission.

The other three people charged in the case are Italian-Thai Development employees Yong Dodkhruea, Nathee Riamsaen and Thanee Thummat.

Mr Yong faces the same charges as Mr Premchai, plus an additional charge of colluding to possess firearms and ammunition without permission. Ms Nathee, who served as a cook during the poaching trip, faces almost all the charges recommended by police, except for colluding to hunt wildlife. Mr Thanee faces the same charges Mr Yong does, plus another charge for colluding to hunt wildlife.

The indictment will also claim damages from all four totalling 462,000 baht, payable to the National Parks, Wildlife and Plant Conservation Department.

Financial compensation for the four defendants' alleged violation of the Environment Act will have to be pursued in a civil suit, Ms Somsri said.

"If Provincial Police Region 7 agrees with the charges, the case will be forwarded to Thong Pha Phum Provincial Court and the suspects will be arraigned. If not, the Office of the Attorney-General will make the call," she said. Prosecutors will draft the indictments while they await reaction from the police.

Deputy police chief Srivara Ransibrahmanakul said police would send a letter to object to the decision.

"Police remain steadfast in our original decision [to press 11 charges]. However, we accept the public prosecutor's decision to drop charges on colluding to commit cruelty to animals and colluding to possess firearms and ammunition without permission," Pol Gen Srivara said.

The Office of The Attorney-General Immediately came out to defend the Office of Public Prosecution Region 7's decision.

"Contrary to criticism in social media, public prosecutors did not drag their feet or try to delay the case. They worked swiftly, fairly and cautiously," Prayuth Phetchkhun, deputy spokesperson of Office of the Attorney-General told journalists.

A major conservationist group monitoring the case also accepted the public prosecutor's decision.

"We are not surprised. Despite five charges being dropped, public prosecutors are still pressing six charges relating to hunting protected wildlife," said Ornyupa Sangkama, chief of the academic section and an environmental law expert at Sueb Nakhasathien Foundation.

Social activist Tanat Thanakitamnuay, who spearheads a graffiti campaign for fair legal action against the poachers, said, "I believe that the recent development in Premchai's case is fair and transparent."