Ethiopia’s Prime Minister Abiy Ahmed has accused the Tigray People’s Liberation Front (TPLF) of starting to fight along aid corridors in the war-torn northern Tigray region. The TPLF, the former ruling party of Tigray which was ousted in November by the army, has since joined forces with other groups to form the rebel Tigray Defence Force (TDF). The rebels captured the regional capital Mekelle last month and the government withdrew its troops and unilaterally declared a "humanitarian ceasefire" to allow farming activity to take place and for aid to be delivered. But the TPLF demanded a negotiated truce, with conditions including the complete withdrawal of Eritrean troops and the regional Amhara forces. In his statement, Mr Abiy also accused the international community of silence about what he said was the TPLF’s recruitment of child soldiers - his first comments on the issue since Tigrayan forces launched their new offensive. They follow remarks by military spokesman Col Getnet Adane, who said that the army was ready to take measures if it received orders. The TPLF said this week that it had recaptured the towns Korem and Alamata along Tigray's southern borders with the Amhara region. The Amhara government has recalled retired members of its security forces as fighting escalates in the disputed areas on its border. On Monday, the United States said it was “gravely concerned” about the intense fighting along the Amhara-Tigray border and reiterated its call for a negotiated ceasefire. There are fears that renewed fighting is going to hinder the delivery of humanitarian aid for hundreds of thousands caught in the crossfire. Last week, UN officials said the fighting had resulted in a famine that was affecting more than 400,000 people. South Africa Zuma riots: Long queues for fuel and food have formed South Africa Zuma riots: Looting and unrest leaves 72 dead Iraq hospital fire Tragedy: Death toll now climbs 92; 100 more injured