"The [regime of Ethiopian Prime Minister Abiy Ahmed Ali] has launched an offensive against our positions in the Southern front," TPLF spokesman Getachew Reda said on Twitter.
The official forces attacked the rebels from the Amhara region, which shares a border with Tigray in the south, the TPLF said.
Meanwhile, Ethiopian authorities denied the accusations, blaming the forces from the rebellious region for resuming fighting and attacking first.
"Ignoring all of the peace alternatives presented by the government, the terrorist group TPLF continued its recent provocations and launched an attack this morning at 5 a.m. [02:00 GMT] on the eastern front in Bisober, Zobel, and Tekulesh directions," the Government Communication Service said on Twitter.
In June, the Ethiopian prime minister announced the formation of a committee to hold negotiations with the TPLF.
Ethiopia has been struggling with a violent internal conflict since November 2020, when the central government accused the TPLF of attacking its military base and launched an anti-terrorist operation in the region. In June 2021, the rebels of the TPLF seized the city of Mekelle, the administrative regional center, and the government declared an unconditional ceasefire. However, the rebels launched a new offensive soon after and took control of the southern part of Tigray and the neighboring Amhara region. The ongoing conflict has claimed tens of thousands of lives, displaced millions of people, and caused a dire humanitarian crisis across the country.