Muhammad Afzal, a resident of Al-Faysal Town neighbourhood near the airport, said he was watching TV with his family when he heard something fall on the roof of his house at 9.30 pm last night.
"I rushed upstairs and found a dead man," he said.
People from the neighbourhood gathered at his home following the "very unusual" incident, Afzal said.
Police came to his home and took the body to the city morgue.
Police officer Rana Irhaam said: "The circumstantial evidence suggests that the man, believed to be in his twenties, fell from a considerable height. Our initial investigations suggest that the man fell from a cargo plane from a height of not less than 700 feet after it took off."
Doctors at the morgue had confirmed that all parts of the body of the unidentified man were "badly smashed", Irhaam said.
An official of the Civil Aviation Authority, who spoke on condition of anonymity, said the incident occurred minutes after a cargo flight took off from Allama Iqbal International Airport for Dubai.
He said: "It was probably a case of human smuggling. Someone in the airport helped the unfortunate young man to stow away in the cargo plane."
An investigation had been launched into the incident, he said.
A large number of Pakistani youths pay huge amounts of money to traffickers to arrange for them to travel abroad, especially to European countries.
Since human smuggling by air has become increasingly difficult, many traffickers use land routes.
According to the Federal Investigation Agency, many Pakistanis try to enter Greece via Turkey and Iran.
"An attempt to stow away in the wheels of a plane is most unique," said an FIA official.
The agency would investigate the matter, he said.
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