ISLAMABAD, Pakistan — A Pakistani newlywed has been arrested and charged with murder in the poisoning of 17 people, including several of her in-laws, in what officials described as an attempt to escape from a forced marriage.

The woman, Aasia Bibi, 21, and a man identified as her boyfriend were accused of having intentionally put rat poison into milk that was served to family members at a gathering.

Ms. Bibi, who appeared in a court in Punjab Province, told reporters she had begged her parents not to force her to marry, but her pleas were ignored. She has been charged under the country’s antiterrorism law and was placed in pretrial detention.

After consuming the tainted milk two weeks ago, 27 members of the extended families were hospitalized. Seventeen of them, including a 4-year-old, a 7-year-old and Ms. Bibi’s husband, Muhammad Amjad, 23, died, officials said.

The couple was married six months ago, the police said.

“But she was not happy with the marriage,’’ Jam Abdul Razzaq Klasra, a local police official, said in a telephone interview. Ms. Bibi was in love with another man, Muhammad Shahid, he said.

The families of Mr. Amjad and Ms. Bibi live on the same street in Malawat, a remote village in the Muzaffargarh district. Because there is not a hospital nearby, the family members who became ill were treated initially by a hakim, a local physician using traditional remedies. When their conditions deteriorated, they were taken to a hospital in Multan.

Mr. Klasra, the police official, said the head of one of the families suspected that the milk had been contaminated. Ms. Bibi was the only person at the family gathering who did not drink the milk, investigators learned, he said.

“As we investigated deeper, we learned that the relations between Aasia and her husband were strained,” Mr. Klasra said.

After the police took Ms. Bibi in for questioning, she confessed to having mixed pellets of rat poison into the milk, he said.

She told the police that Mr. Shahid had promised to marry her and that one of his aunts had been involved in planning the poisoning, Mr. Klasra said.

The aunt has also been arrested.

Arranged marriages are still common in Pakistan, particularly in rural areas. When couples attempt to marry for love, outside of family arrangements, they are often killed by family members.

“Arranged marriage is a source of comfort for most parents here as they feel that the existing close ties between families will strengthen the new relationship,” said Salman Sufi, an aide to Punjab’s chief minister.

Societal changes and young people’s increased exposure to the outside world has led some to question the logic of arranged marriages and even to rebel against the tradition, he said.

“The result often is a severely fractured relationship between spouses or catastrophic aftereffects, like we witnessed in this case,” Mr. Sufi said.