Police in Pakistan on Thursday arrested 15 people allegedly involved in the sexual assault of a YouTuber girl on Independence Day at the historic Minar-i-Pakistan, after the incident sparked nationwide outrage and drew international condemnation.

The incident took place on August 14 when hundreds of youngsters were celebrating Independence Day at Azadi Chowk near Minar-i-Pakistan in Lahore.

Hundreds of young men can be seen in the videos throwing the girl in the air for fun, dragging her, tearing her clothes and molesting her.

Politicians from all parties and members of civil society have strongly condemned what many of them called "sexual terrorism".

Police had registered a case on Tuesday against 400 unidentified men for assaulting the girl and her companions on August 14.

"We have arrested 15 suspects after identifying them through video footage. The footage has been sent to the National Database and Registration Authority (Nadra) for identification of the remaining suspects," a Lahore Police officer told PTI on Thursday.

He said non-bailable clauses have also been added to the FIR to ensure that the suspects do not get any legal relief.

The victim said in the FIR she and six other members of her YouTube channel visited Azadi Chowk near Minar-i-Pakistan Lahore to record a video clip of the Independence Day celebrations.

"We were shooting the clip when a good number of youngsters started teasing me. They were joined by more and more. They stripped and molested me. They dragged and tossed me up in the air for fun. And this ordeal continued for two and a half hours before a security personnel rescued me," she said.

Prime Minister Imran Khan has also taken notice of the sexual assault of the girl and ordered IGP Inam Ghani to arrest those responsible for the assault.

Opposition Leader in the National Assembly Shehbaz Sharif termed the incident shameful.

"Deeply disturbed at the harassment of a young woman & her companions by hundreds of people at Minar-i-Pakistan. What is more worrying is the direction our society is headed. The recent anti-women incidents are a reminder that malaise is deep-rooted. Very Shameful!" he said.

Former prime minister Nawaz Sharif's daughter Maryam Nawaz demanded justice for the girl.

"Heart-wrenching scenes at Minar-i-Pakistan warrant collective introspection. We as parents, teachers & leaders need to reflect upon the upbringing of our youngsters to make public spaces safe for women. Those involved must be dragged to justice to create deterrence for future," she tweeted.

Opposition PPP Chairman Bilawal Bhutto-Zardari tweeted: "The assault of a young woman by a mob at minar e pakistan should shame every Pakistani. It speaks to a rot in our society. Those responsible must be brought to justice. The women of Pakistan feel insecure and it is all our responsibility to ensure safety and equal rights to all".

Bilawal''s sister Aseefa Bhutto-Zardari tweeted: "We cannot continue to bury our heads in the sand. #Pakistan is not safe. Not for our women. Not for our children. Our children aren't safe from rape even in death. This is the disgusting shameful reality."

The United Kingdom Research Centre and Pakistani Women's Media Network strongly condemned the heinous incident, saying the men who attacked the girl at a public place proved that public spaces were not safe for women.

"We demand immediate action against the culprits. They should be arrested and brought to justice," they said.

The organisations also slammed some television anchors for acting irresponsibly while covering the incident and visiting the girl's house and getting "themselves photographed while placing their hands on her head".

"We appeal to all media to kindly respect the privacy of the suffering woman," they said.

"With this incident, the claims that Pakistan is the safest place for women and that we know how to respect women don't hold true. Time to act and prove your claims is now," the British organisation said.

Amnesty International also condemned the assault.

"The time when the country is reeling from the murder of Noor Mukadam and Quratulain, this episode has compounded the horror even more.

"Authorities must immediately hold the perpetrators to account and provide greater protection for women in public spaces, which women have every right to but are prevented from accessing fully, for fear of attacks exactly like this," it said.