NEW DELHI — Security forces were hunting through forests in southeast India Monday for Maoist rebels after a fierce gunfight left 21 rebels dead and two policemen wounded. The gunfight broke out late Sunday after police received a tip that 60 Maoist rebels were gathered in forests on the border of Odisha and Andhra Pradesh states. The gunfight lasted an hour before the rebels scattered into the dense forests. At daybreak Monday, police and paramilitary soldiers launched a search for them. The rebels, who have been fighting for more than three decades demanding land and jobs for tenant farmers and the poor, say they are inspired by Chinese revolutionary leader Mao Zedong. Considered India’s biggest internal security threat, they operate in 20 of India’s 28 states and have thousands of fighters.