The scene outside the court in Lahore after the stoning - photo: World Breaking News via YouTube

The relatives had previously accused Farzana's husband, Muhammad Iqbal, of kidnapping her and had filed an action against him at the court.

But Farzana testified that she had married Muhammad of her own freewill and police confirmed that the couple were engaged for several years before they got married.

Farzana was three months pregnant at the time of the attack, which took place as she and Muhammad arrived at the court to register their union.

The group started attacking both Farzana and Muhammad, who managed to escape.

"We were in love," Farzana's husband told the Associated Press. "I simply took her to court and registered a marriage."

The victim's father handed himself in to police after the stoning but other family members involved in the incident walked free, police said.

Police investigator Rana Mujahid vowed to tracked down all those involved in the "heinous crime."

He said the woman's father was unrepentant and quoted him as claiming, "I killed my daughter as she had insulted all of our family by marrying a man without our consent, and I have no regret over it."

Pregnant woman stoned to death after marrying for love in Pakistan