YEREVAN (Reuters) - Armenian Foreign Minister Zohrab Mnatsakanyan resigned on Monday, the ministry said, in a sign of political fall-out in the ex-Soviet republic after a ceasefire in the Nagorno-Karabakh conflict that locked in territorial gains for Azerbaijan.Prime Minister Nikol Pashinyan’s government has faced a backlash over the ceasefire that ended six weeks of fighting, with thousands of protesters last week demanding he resign. On Monday, hundreds of protesters rallied in the capital Yerevan. The ceasefire signed by leaders of Armenia, Azerbaijan and Russia on Nov. 10 halted military action in and around Nagorno-Karabakh, an enclave internationally recognised as part of Azerbaijan but populated by ethnic Armenians. Some 2,000 Russian peacekeeping troops are now being deployed to the region. Armenian President Armen Sarkissian said Pashinyan’s government should step down and a snap parliamentary election should be held. “Taking into account the current situation, taking into account public demands, it is obvious that in order to avoid internal political upheavals, the holding of early parliamentary elections is inevitable,” Sarkissian said in address to the nation. He said there should be an interim government of national unity. However, the president does not have much power and his statement might be viewed as more of a recommendation. Pashinyan has rejected calls to step down. For over 25 years until fighting over Nagorno-Karabakh resumed on Sept. 27, ethnic Armenians held military control over the entire pocket and swathes of Azeri territory ringing it. But when the guns fell silent, they had lost much of the enclave - including its second city Shushi, which Azeris call Shusha - as well as adjoining terrain.