Desperate family members have smashed open the coffin of a pregnant teenager who was reportedly buried alive and could be heard screaming inside her grave.

Footage from early July shows a group trying to free Neysi Perez, 16, from her concrete tomb one day after she was buried in a Honduras cemetery, Spanish news broadcaster Primer Impacto reports.

After opening the tomb with sledge hammers, rescuers discovered that the glass viewing window on her coffin had been smashed and that Ms Perez's fingers were bruised, claimed relatives .

Ms Perez, who was buried in her wedding dress, was rushed to a nearby hospital in San Pedro Sula, but doctors were unable to save her and she was pronounced dead.

The day after her funeral, Ms Perez's husband Rudy Gonzales is said to have been visiting her grave at La Entrada General Cemetery when he heard muffled screams.

"As I put my hand on her grave I could hear noises inside. I heard banging, then I heard her voice. She was screaming for help," Mr Gonzales told Primer Impacto .

"It had already been a day since we buried her. I couldn't believe it. I was ecstatic, full of hope."

A worker at the cemetery, Jesus Villanueva, claimed he had also heard strange noises coming from the tomb.

"I convinced myself that the screams were coming from somewhere else. I never imagined that there was someone alive in there," said Mr Villanueva.

Days earlier Ms Perez was found collapsed on the floor of her La Entrada home after going to the bathroom in the middle of the night. She was reportedly three-months pregnant.

Her parents discovered her unconscious and foaming at the mouth, and believed their teenage daughter may have been possessed.

They took her to a local priest who attempted an exorcism only for the girl's body to become lifeless. Ms Perez was then taken to hospital where doctors declared that she was dead.

Doctors believe that Ms Perez could have suffered a severe panic attack, which may have temporarily stopped her heart and led to the incorrect diagnosis that she was dead.

Another theory is that the pregnant teenager had a cataplexy attack. Sufferers experience an abrupt temporary loss of voluntary muscle function, typically triggered by overwhelming feelings of stress or fear.