Yemeni military forces have mounted a fierce crackdown against armed tribesmen accused of bombing oil and electricity lines in the southwestern governorate of Marib. Meanwhile, final preparations are underway in capital city Sanaa for the National Dialogue Conference, scheduled to begin on Monday. Military sources have told Arabstoday that a security plan has been developed to confront gunmen involved in the bombing the oil pipelines in Safer Field. The electricity network has come under attack once again, after Ministry of Electricity engineers had repaired the damage on Wednesday. Yemeni authorities have increased the presence of security personnel around the energy sites, and have threatened tribesmen with arrest, in a bid to bring an end to the bombings. Sources have confirmed that around 30 Yemeni army tanks and armoured vehicles have been deployed in the region, along with dozens of security and military officers. Attacks on oil and gas pipelines by al-Qaeda or by tribesmen seeking to win concessions from the central government are common in Yemen, an impoverished country that produces about 300,000 barrels of oil a day, mostly for export. In December, the army launched an offensive against tribesmen suspected of repeatedly sabotaging the pipeline, sparking clashes which left 17 people dead. Elsewhere, Yemen’s defence ministry has established a control room to provide security during the upcoming National Dialogue Conference, which begins at the presidential palace in Sanaa on Monday. The control room is expected to be the security base for both military and police forces during the duration of the conference. The Ministry of Defence has issued a statement on its official website saying it would take any "measures necessary" to make sure the national dialogue sessions are conducted without any security problems. Sources have told Arabstoday that several regional and international figures are participating in the opening session on Monday, with United Nations Secretary-General Ban Ki-moon, and foreign ministers of five UN Security Council members expected to attend the conference.   The dialogue, which runs for six months, brings together 565 representatives from various political groups.