One of the more than 200 schoolgirls kidnapped by Boko Haram fighters in the town of Chibok in 2014 was found by Nigerian soldiers on Saturday, according to the army.

The rescue comes weeks after 21 other Chibok girls were released by the armed group following negotiations with the government brokered by the International Red Cross and the Swiss government.

READ MORE: Kisses, tears as freed Chibok girls reunite with families

Army spokesman Sani Usman said the girl, Maryam Ali Maiyanga, was discovered by troops who were screening escapees from Boko Haram's base in the Sambisa forest on Saturday morning in Pulka, in Borno state.

Usman said Maiyanga was carrying a 10-month-old baby when the soldiers found her.

"She has been taken to the unit's medical facility for [a] proper medical check up," said Usman.

The news was welcomed by the Bring Back Our Girls lobby group campaigning for the release of all the abductees.

In a statement, the campaigners said "preliminary investigations" showed the girl was number 198 on its register of the kidnapped girls.

They added she was from Askira Uba, a district of Borno state, and was abducted along with her twin who is yet to return.

Boko Haram seized 276 pupils from the Government Girls Secondary School in Chibok on April 14, 2014.

Fifty-seven managed to escape in the immediate aftermath of the abduction, but nearly 200 other girls are still missing. The government has vowed to rescue those still held.

Army offensive

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The kidnapping has become a major political issue in Nigeria, with the government and military criticised for their handling of the incident and failure to rescue the girls.

In recent weeks, Nigeria's army has been carrying out a large-scale offensive in the vast woodland area and other parts of Borno state, the epicentre of Boko Haram's violent campaign.

Usman said troops killed 14 suspected Boko Haram fighters on Friday during a clash.

"We lost an officer and four soldiers, while four other soldiers sustained various degrees of injuries during the encounter," he said.

About 2,000 girls and boys have been abducted by Boko Haram since 2014, with many used as sex slaves, fighters and even suicide bombers, according to Amnesty International.

The unrest in Nigeria's mainly-Muslim north has killed at least 20,000 people and made more than 2.6 million homeless since 2009.

Source: Al Jazeera News And News Agencies