(Adds government statement, paragraphs 7-9) By Stephanie Hancock N'DJAMENA, Nov 25 (Reuters) - Armed rebels and unidentified gunmen entered at least two towns in eastern Chad at the weekend and beat two foreign aid workers after rebel factions abandoned a month-old ceasefire, humanitarian staff said on Sunday. The unrest underlined deteriorating security in the area where European Union peacekeepers hope to start deploying in the next few weeks to complement a hybrid U.N./African force planned for Sudan's violent Darfur region, over Chad's eastern frontier. Leaders of Chad's two biggest rebel movements, the Union of Forces for Democracy & Development (UFDD) and the Assembly of Forces for Change (RFC), said on Friday they would break a ceasefire from Sunday -- a month to the day since the groups signed a Libyan-brokered peace deal with President Idriss Deby. A few hours later, on Saturday, several UFDD vehicles entered the town of Hadjer Hadid, 70 km (44 miles) east of the city of Abeche, triggering a security alert and prompting French and Chadian helicopters to take off in vain pursuit. Aid workers in the area said the rebels exchanged fire with government security forces in Hadjer Hadid, although UFDD leaders said their fighters entered the town only to get water. "We will attack Deby's forces if they continue to provoke us," UFDD Secretary General Abakar Tollimi said by satellite phone. GOVERNMENT BLAMES SUDAN The government said rebels attacked from positions in Sudan. Each country has accused the other of backing rebels. "Their forces crossed the Chad-Sudan border to attack gendarmes tasked with protecting refugee camps in several small border settlements, including Hadjer Hadid," Communication Minister Hourmadji Moussa Doumgor said in a statement. "Chad places responsibility on Sudan, which has an obligation to contain armed elements of all the signatories to the Sirte accord until the implementation of the central clause of the accord, which is ... disarmament," he said. After the Libyan-backed peace deal was signed a month ago, speculation grew last week that rebels might be preparing fresh attacks when the president cancelled a high-profile official visit to the United States at less than 48 hours' notice. French forces based in Abeche stepped up security at the airport after the attack, aid workers in the city said. Humanitarian work was suspended until further notice at two refugee camps near Hadjer Hadid, a U.N. official in Abeche said. "We are still on alert as the situation is not clear," said the official, who declined to be identified. Aid workers are helping hundreds of thousands of Sudanese and Chadians in the east of oil-producing Chad, which has been drawn into sporadic violence stemming from the conflict in Darfur and armed rebellion against Deby's 17-year-old rule. Armed attackers in military fatigues overran an aid compound late on Saturday in the small town of Kou Kou Angarana, 180 km (110 miles) southwest of Abeche, humanitarian staff said. The gunmen, whose identity was unclear, used the butt of a rifle to beat two foreign aid workers for the French branch of Medecins Sans Frontieres and Oxfam International and a Chadian security guard was hit in the leg by a bullet, they said. Most aid workers there pulled back to the nearby town of Goz Beida, and would decide on any broader evacuation on Monday. (Additional reporting by Dany Danzoumbe; Editing by Alistair Thomson and Andrew Dobbie)
