At least six army soldiers were killed after secessionist gunmen attacked a military post in Yemen's southeastern province of Hadramout on Sunday, a police officer told Xinhua. The secessionist gunmen fought fierce clashes with army soldiers of the 37th Armored Brigade stationed in the eastern parts of Mukalla, the capital city of Hadramout province, the local police officer said on condition of a anonymity. "The secessionist attempted to gain access to the army location. But the soldiers have successfully repelled them. Six soldiers were killed in the fighting," the police source said. Another army source told Xinhua that the secessionist attackers fired rocket-propelled grenades at the checkpoint, sparking fierce clashes with army troops. A government official in Hadramout province, confirmed the attack but said it was repelled and the situation around the area is calm and under control. Elsewhere, sporadic clashes continued in Hadramout between army forces and small groups of tribesmen near an oil field, the local sources said without giving further details. Last Month, secessionist gunmen attempted to storm several government buildings to hoist a flag of the former South Yemen, sparking fierce clashes, which left several people dead across the southern regions. North and South Yemen unified peacefully in 1990, but the relationship deteriorated in 1994. Calls for separation in the country's southern regions were renewed in 2007. Southerners have been complaining of being marginalized, particularly since they lost the four-month civil war in 1994. Pro- secession protests are on the rise in the south amid a worsening economic situation and allegations of discrimination in favor of northerners. Concerns have increased since the conflicts in southern Yemen are creating instability where al-Qaida could gain foothold.