Sanaa, Dec 17 : At least 20 people were killed and several others injured in intense clashes between Yemen's government forces and tribal fighters in the country's oil-rich province of Marib, a security official said. "Heavy fighting continued between government troops and scores of tribal fighters during the past 24 hours, leaving 12 soldiers and eight armed tribesmen killed and several others injured from both sides," the official told Xinhua news agency. The official said that heavy fighting broke out as the tribal fighters launched an attack and attempted to capture a government-owned oil company in the eastern part of Marib. "The government troops intervened after the tribal fighters set up checkpoints and blocked main roads linking between key areas in Marib. "The clashes are still ongoing sporadically and there are mediation efforts conducted by local social figures to end the internal bloody conflict in Marib," he added. Local residents said that units of the government forces backed by armoured vehicles were deployed heavily in Marib as the tribal fighters continued their escalation against the government despite the tribal mediation. The country's government forces backed by Saudi Arabia control the strategic oil-rich province of Marib and frequently engage in fighting with the Houthi rebel militia in various areas near the city. Yemen's civil war flared in late 2014 when the Houthi group seized control over much of the country's north and forced the internationally recognised government out of the capital Sanaa. /IANS