NEW DELHI (Reuters) - Indian troops exchanged gunfire on Wednesday with separatist guerrillas in a remote northeastern region bordering Myanmar, killing or wounding several of the insurgents, army officials said. The army was carrying out an operation against the separatist group, which is believed to have 2,000 guerrillas battling for an independent Greater Nagaland state carved out of India. An army patrol retaliated swiftly upon coming under heavy fire from the rebels, the Indian Army s eastern command, headquartered in the city of Kolkata, said in a statement.   Heavy casualties reportedly inflicted on NSCN-K cadre,  it said, using an acronym for the group, the National Socialist Council of Nagaland-Khaplang.  No casualties suffered by Indian security forces.  Wednesday s operation was confined to the Indian side of the border, it added.   In 2015, Indian special forces crossed into Myanmar to hunt down guerrillas of the group who had taken shelter in the neighboring country.  That year the group launched a series of attacks on security forces in India s northeast, to scrap a ceasefire it had observed with New Delhi since 2001. In recent years, the militaries of India and Myanmar have built close ties, with each pledging not to allow insurgent groups to shelter in its territory.  India has condemned attacks in August by Rohingya insurgents on security posts in Myanmar s Rakhine state that provoked a military crackdown, causing hundreds of thousands of Rohingya Muslims to flee the country. 