Imphal, Nov. 17 :    Imphal, Nov. 17:  Manipur is set for a political showdown between Speaker Sapam Dhananjoy and chief minister W. Nipamacha Singh, with the ruling United Front of Manipur today deciding to replace the former. Dhananjoy hit back immediately by announcing horticulture minister Thangminlen Kipgen's disqualification from the Assembly. Kipgen is one of the nine legislators of the ruling coalition against whom the Opposition has filed cases pertaining to the violation of the anti-defection law. All the Opposition members are camping at the Speaker's bungalow after Nipamacha Singh 'confined' the ruling members in his residence since Wednesday night. Ministers did not attend their offices for the second day today and the imbroglio continued to affect the state government's activities, sources said. However, information minister and ruling UFM spokesman M. Kunjo Singh claimed that all the ministers are attending office. He circulated a document signed by 37 of the 39 UFM members which stated that they have resolved to 'remove Dhananjoy from the Speaker's post'. However, they made no charges against the Speaker. The state Cabinet has recommended that Governor Ved marwah summon the winter session of the Assembly from December 1. Reacting to the ruling coalition's decision to remove him Dhananjoy Singh said he was unanimously elected by both the UFM and the Opposition members. 'Their decision cannot remove me and I don't know their charges against me as yet,' he added. He said he will announce the verdict of the disqualification cases 'step by step' as he is taking each case separately. Manipur People's Party president O. Joy Singh said the Opposition members are 'guarding' the Speaker from being 'kidnapped' by the ruling coalition. Policemen ambushed Two police officers were killed and four constables injured when unidentified militants ambushed the vehicle in which they were travelling at Kakching in Thoubal district this evening. The ambush was in retaliation to the killing of two rebels by the police this afternoon in the Kakching area, sources said. The rebels ambushed the police team when they were returning to the Kakching police station after conducting the post-mortem of the slain militants. A group of rebels fired at the vehicle, while another group targeted the police station, the sources added. Kakching police station officer in-charge Rupachandra Singh and assistant sub-inspector of police Prabhudayal Singh were killed in the attack.