SANAA (AFP/Reuters) - Heavy clashes between Yemeni tribesmen and elite Republican Guard troops on Wednesday prompted the closure of the capital Sanaa's airport and the diversion of flights, aviation and tribal sources said. "Sanaa's airport has been shut down and flights have been diverted to the airport of Aden," the southern regional capital, the official said. Tribal sources said that heavy fighting erupted near the airport between Republican Guard troops and tribesmen belonging to Arhab, the tribe of hardline cleric Abdul Majid al-Zindani. Meanwhile, Sporadic machine-gun fire rang out for the third day in the sandbagged streets around the mansion of an influential tribal leader who has backed protesters seeking to overthrow the longtime ruler after repeated international mediation failed. Black smoke rose from the compound of Sadiq al-Ahmar, at the centre of the clashes that have killed at least 39 people since Monday, when his guards first exchanged fire with loyalist forces they accused of stockpiling weapons at a nearby school. "What happened was a provocative act to drag us into civil war, but it is limited to the Ahmar sons. They bear responsibility for shedding the blood of innocent civilians," Saleh told selected media including Reuters. "Until this second, they are attacking the Interior Ministry. But we don't want to widen the confrontation," he said. "They have chosen this and they made the wrong decision to confront the state with this kind of violence." The fighting, the most sustained clashes in Sanaa since protests against Saleh's rule began in February, erupted on Monday, a day after the president refused at the last minute to sign a Gulf-brokered deal that would ease him out of power. Saleh has backed out of previous deals, but Sunday's turnabout appeared to have sparked a major reaction, coming after loyalist gunmen trapped Western and Arab diplomats in the United Arab Emirates embassy for hours. Both sides blamed each other for the violence, which the opposition said could start a civil war. The bloodshed dimmed prospects for a political solution to a popular revolt inspired by protests that swept aside the leaders of Egypt and Tunisia.