ADDIS ABABA (Reuters) - Heavy fighting flared in Ethiopia’s northern Tigray region on Wednesday, diplomatic sources said, after the prime minister launched military operations in response to what he said was an attack on federal troops.Tensions have been escalating since September, when Tigray held regional elections in defiance of the federal government, which called the vote “illegal”. In recent days, both sides accused each other of plotting a military conflict. Early on Wednesday, the local ruling party, the Tigray People’s Liberation Front (TPLF), tried to steal artillery and other equipment from federal forces stationed there, Prime Minister Abiy Ahmed’s office said. “The last red line has been crossed with this morning’s attacks and the federal government is therefore forced into a military confrontation,” it said, adding that the aim was to prevent instability engulfing the country and region. Tigray’s population makes up 5% of Ethiopia’s more than 110 million people, but the area is wealthier and more influential than many other, larger regions and has a well-trained army. Abiy’s spokesman, Billene Seyoum, told Reuters later that military operations in Tigray had commenced, without elaborating. Two diplomatic sources in Addis Ababa said heavy fighting, including artillery fire, had broken out in the northern region, which borders Eritrea. The prime minister’s office said the federal government had declared a six-month state of emergency in Tigray to be overseen by the chief of staff of the armed forces.Tigrayans’ influence has waned since Abiy came to power in 2018. Many senior Tigrayan officials have been detained, fired or sidelined, in what the federal government describes as a clampdown on corruption but Tigrayans see as a means to quell dissent. Last year, the TPLF quit Abiy’s ruling coalition.