Chad’s President Idriss Deby has said the fight against Boko Haram militants is being hampered by poor co-ordination between his country and Nigeria.
Mr Deby said that some progress had been made since Chad intervened against the Islamist insurgents.
But had the two countries’ armies worked together Boko Haram would have been wiped out by now, he said.
The fight against Boko Haram has drawn in Nigeria’s neighbours as the militants threaten their security.
Chadian forces crossed into north-eastern Nigeria earlier this year and fought the militants in towns of Damasak and Baga.
This helped the Nigerian military offensive and since February much of the territory taken over by Boko Haram in the previous year has been recaptured.
“If we want to continue the fight we’ll have to make sure that our two armies work together,” Mr Deby said on a visit to Nigeria where he met President Goodluck Jonathan.
“This is the only way that we can get results,” he added.