A Pakistani teenager allegedly burned alive for refusing a marriage offer actually committed suicide, police said Friday, in a statement slammed by a prominent rights activist and the girl's father.

The death of 19-year-old Maria Sadaqat made international headlines after claims she was tortured then set alight in the country's conservative northeast for refusing the proposal.

Hundreds of women are murdered by their relatives in Pakistan each year on the pretext of defending what is seen as family honour.

Sadaqat was said to have been attacked by a group of people near the summer hill resort of Murree, outside the capital Islamabad, in late May, and died several days later.

At the time police said she gave a statement before she died naming the man who had allegedly proposed, as well as his father, among others as her attackers.

But on Friday police discounted her dying words, claiming Sadaqat and the man had been in a "relationship" for years and that in thousands of text messages exchanged between the pair she had begged him to marry her.

She had also warned in a text message that he would be held responsible for her suicide, officials said.

The petrol used to set her alight, police added, came from her father's workshop, and no forensic evidence supported the claim she had been attacked.

Investigation head Abubakar Khudabaksh confirmed the report.

But the girl's father accused police of manipulating the investigation.

"This is very disturbing and shocking that police are changing the facts and manipulating the investigation in the favour of accused party," Sadaqat Hussain told AFP.

"We are poor. What can we do?"

Prominent women's rights activist and lawyer Asma Jehangir, who has formed a committee to examine the incident, also rejected the report.

"This case does not appear to be a suicide. (The) girl's hands were not burned," she said.

"And if she wanted to commit suicide she would have swallowed some poison or shot herself instead of putting herself in such pain and agony," Jehangir continued.

"Also, there is the dying declaration of the girl," she said, pointing out that some of the accused men had gone on the run after the incident rather than coming forward to say Sadaqat's statement was false.

She called on the government to launch a fresh investigation into the death.