Boko Haram is offering to free more than 200 Chibok girls in exchange for the release of their leaders in detention, a rights activist has told The Associated Press.

The activist said Boko Haram’s current offer is limited to the girls from the school in Chibok whose mass abduction in April 2014 ignited worldwide outrage.

The new initiative reopens an offer made last year to the government of former President Goodluck Jonathan to release the 219 students in exchange for 16 Boko Haram detainees, the activist said. He spoke on condition of anonymity because he was not authorised to talk to reporters on this sensitive issue.

Fred Eno, an apolitical Nigerian who has been negotiating with Boko Haram for more than a year, told the AP that “another window of opportunity opened” in the last few days, though he could not discuss details.

He said the recent slew of Boko Haram bloodletting is consistent with past ratcheting up of violence as the militants seek a stronger negotiating position.

Presidential adviser Femi Adesina said on Saturday that Nigeria’s government “will not be averse” to talks with Boko Haram. “Most wars, however furious or vicious, often end around the negotiation table,” he said.

Eno said the five-week-old administration of President Muhammadu Buhari offers “a clean slate” to bring the militants back to negotiations that had become poisoned by the different security agencies and their advice to Jonathan.

•Photo shows some of the Chibok schoolgirls as appeared in a Boko Haram video.