Fifteen women and six children kidnapped by Islamist militants in the gas-rich northern Mozambican province of Cabo Delgado have been rescued by the army. Most of them had been abducted from the island of Matemo last week, police chief Bernardino Rafael said. Recent fighting meant the security forces knew where the militants were located, so with the assistance of helicopters they were able to track down and isolate the abductees, he said. They will be taken back to Matemo, which has suffered militant attacks since October. But the police chief said the island was now safe. The militants, known locally as al-Shabab, or the youth, have launched a series of attacks on villages and towns in the area over the past three years. They tend to kidnap women and children, who are used as sex slaves and to transport looted goods following attacks.