A 14-year-old Nigerian girl stands accused of killing four people with rat poison, including her 35-year-old husband, at a ceremony celebrating her wedding.

Wasila Tasi'u, a girl from a rural mostly-Muslim area of northern Nigeria is accused of the premeditated murder of her husband, Umar Sani, as well as three other people. If found guilty she could face the death penalty.

Human rights campaigners say that Tasi'u had married a man more than twice her age, possibly against her will and should be considered the victim of a crime rather than the perpetrator of one.

The first witness called by the prosecution was the seven-year-old sister of one of Sani's other wives. She testified that she had been told by Tasi'u to fetch rat poison to help deal with a rodent infestation in the house. "She said rats were disturbing her in her room," she said in court.

The seven-year-old added that she had been given money by Tasi'u on the day that Sani and three other people died.

According to the prosecution, Tasi'u laced a dish she was preparing for the post-marriage celebration with poison, possibly because she "regretted" her marriage, ABC reports.

Abdulrahim Ibrahim, a neighbour who had been invited to the celebration, said that he had tried a small amount of the food allegedly prepared by Tasi'u but stopped eating because it looked and tasted peculiar.

"When he brought the food (I) noticed some sandy-like particles, black in colour," he told the court.

He ate a small amount of the bean paste but "was not comfortable with the taste. It was only [Sani] who continued eating."

Ibrahim said that Sani quickly became unwell, so he escorted him home. It was only later that he learnt three other guests who ate the food at the reception had died suddenly.

The judge, Mohammed Yahaya, entered a plea of not guilty on behalf of Tasi'u at a preliminary hearing that the 14-year-old had failed to attend, the Daily Mail reports.

The prosecution says that it has six more witnesses to call, but the case has been adjourned until 22 December.