One of the abducted Chibok schoolgirls who was able to escape Boko Haram has appealed for help in bringing back the other girls who remained in the hands of the militants.

The group of 276 female students were kidnapped in April last year by Boko Haram.

Two of the girls escaped the group by jumping out of a moving truck while they were being transported. They hid in a bush until they were rescued the next day and brought to safety.

One of the escapees, who uses the pseudonym "Saa" to protect her family in Nigeria, is now in the United States to continue her studies through the help of a non-profit organisation.

According to the National Journal, Saa delivered a speech on Wednesday in front of the US Capitol to commemorate a year since the schoolgirls were kidnapped by Boko Haram.

In her speech, Saa described her plight at the hands of Boko Haram and how coming to America reminded her of her classmates who remain captive of the Nigerian Islamist group.

"When I came to America, I came to Washington D.C. and found a story that American people say: Give me liberty or give me death. When I heard that, I remembered the time I decided to jump out of the truck, that I'd rather die," Saa said.

The former Boko Haram captive told the gathered audience that while she is now free in the United States and able to continue her studies, most of her classmates are not fortunate enough to enjoy the same freedom.

She is calling for help from the international community for the immediate rescue of her captive classmates. 

"I'm pleading everybody all over the world. And I'm pleading the international community to do all our best and try to brings those girls back to school," Saa implored during her speech.

"We really want them now. Not tomorrow. Not day after tomorrow, not next year. We want them now to come back to school," she added.