Around 10 soldiers were killed and others wounded early Tuesday when jihadists attacked an army position in western Chad, the presidential office said.
The attack took place near Ngouboua in the Lake Chad area, a vast marshy region shared by Chad, Niger, Cameroon and Nigeria that has been battered by Boko Haram and the Islamic State West Africa Province (ISWP).
The unit had been sent to help set up an advance position on Bouka-Toullorom island when it was "attacked by elements from the Boko Haram sect," presidential spokesman Brah Mahamat said.
The Chadian authorities routinely refer to jihadists as Boko Haram regardless of their affiliation.
"The 10 or so dead, and the wounded, are members of the defence forces," he said.
The problems in Lake Chad stem from an insurgency launched by Boko Haram in northeastern Nigeria 13 years ago that has killed more than 40,000 people there and displaced around two million.
In 2014, Boko Haram seized islands in the marshland and began using them as boltholes. In 2020, most of these islands were taken over by ISWAP, which had split from Boko Haram.
The vast semi-desert African country has been ruled since April 2021 by General Mahamat Idriss Deby Itno, 38.
He took over after his father, president Idriss Deby Itno, who ruled with an iron fist for 30 years, died during an operation against rebels in the north of the country.
In a visit to the Lake Chad region earlier this month, General Deby said the jihadists "no longer have the strength to hit bases" and as a result were concentrating their attacks on the civilian population.