BANGKOK (REUTERS) - A three-star Thai army general has denied charges against him for offences related to human trafficking, Thailand's police chief said, the latest in a series of arrests aimed at stamping out people smuggling.

Thailand has issued 84 arrest warrants as it cracks down on smuggling and trafficking of humans through its territory.

The clampdown has sparked a humanitarian crisis in Southeast Asia as criminals have abandoned boats full of people rather than risk transporting them through Thailand.

Thai Lieutenant General Manas Kongpan is the most senior official to be charged to date in the operation. Police say they have made 51 arrests.

Manas was in police custody on Wednesday after turning himself in. He was suspended on Monday when police ordered his arrest. "He says he has no involvement, which is a denial (of charges)," Thai national police chief Somyot Poompanmuang told reporters on Wednesday.

Manas is the only soldier who has been charged with offences related to human trafficking, said deputy police chief Aek Angsananont.

More than 50 Thai police have been transferred from their posts over suspected links to trafficking and smuggling.

About 4,000 migrants have landed in Indonesia, Malaysia, Thailand, Myanmar and Bangladesh since Bangkok launched its crackdown last month.

The United Nations estimates some 2,000 migrants may still be adrift in the wake of Thailand's May sweeps, after traffickers chose to abandon them rather than take them ashore and risk arrest.