The truck driver -- Hari Ram -- was held on Wednesday and his vehicle was also impounded, they said.
According to police, the truck was stopped during picket checking at South Extension-1. The truck's windshield had a sticker that read "Medicine Emergency Services Provider".
When questioned, the truck driver initially claimed that he was going to supply medicines but failed to show any papers to police.
Later when police personnel began inspecting his truck, he admitted to ferrying migrant labourers, Deputy Commissioner of Police (South) Atul Kumar Thakur said.
Police found 33 migrant workers sitting inside the truck in "inhuman conditions", he said.
The workers told police that they hired the truck at Rs 1,800 per person and had paid Rs 20,000 advance to the vehicle owner, he added.
These 33 people are daily wage workers residing in Delhi's Ranhola and Mayapuri areas, Thakur said.
The truck driver was arrested and a case was registered against him at the Kotla Mubarakpur police station under sections 188 (for disobedience to order duly promulgated by public servant), 269 (negligent act likely to spread infection of disease dangerous to life) and 270 (malignant act likely to spread infection of disease dangerous to life) of the Indian Penal Code and Section 3 of the Epidemic Act, the DCP said.
Of the 33 workers, 29 were handed over to the Ranhola police station, while four others were handed over to the Mayapuri police station for sending them back to their rented accommodation, he said. AMP SNESNE