NAIROBI/ADDIS ABABA (Reuters) - The Ethiopian government rebuffed an African effort to mediate on Saturday, saying its troops had seized another town in their march towards the rebel-held capital of northern Tigray region.More than two weeks into Prime Minister Abiy Ahmed’s offensive, the government says Tigrayan forces are bulldozing roads and destroyed bridges to hold up the advance on regional capital Mekelle, home to about half a million people. The Tigrayans have promised “hell” for their advancing enemies. They have denied destroying bridges but were not reachable for comment about ploughing up roads. Hundreds, possibly thousands, have died and more than 30,000 refugees have fled to Sudan since the conflict erupted on Nov. 4. The fighting has spread beyond Tigray, whose forces have fired rockets at the neighbouring Amhara region and the nation of Eritrea, spurring concern of a wider war and the splintering of multi-ethnic Ethiopia. Abiy’s government has said it will soon reach Mekelle after taking various surrounding towns. On Saturday it said Adigrat had also fallen, about 116 km (72 miles) north of Mekelle. The Tigray People’s Liberation Front (TPLF) rebels said nine civilians had died among heavy casualties in artillery hits on Adigrat.The government could not immediately be reached for comment, but has previously repeatedly denied targeting civilians. Assertions on all sides are hard to verify because phone and internet connections have been down since the beginning of the conflict and media are largely barred. Eritrea denies TPLF allegations it has sent soldiers over the border to back Abiy’s offensive against the Tigrayan forces, who are also an old foe of Eritrea’s. Graphic: Map of region -