Yemeni Houthi militants attacked the Headquarter of General Secretariat in Sanaa late Wednesday, where national dialogue was held, Sky News Arabia reports. Houthis stormed the building after threatening the guards and robbed its contents, that held documents and testimonies concerning the UN-sponsored dialogue. The recent escalation of Houthi's action is believed to be in response to the criticism of UN envoy, Gamal bin Omar of Houthis. He accused them of eliminating negotiations between the parties in conflict, and violating UN resolutions. Bin Omar expressed his disappointment that Houthis didn't withdraw from the institutions seized in Sanaa, or lift the siege on the ministers, but he affirmed at the same time that negotiations are making an advance. Houthis affirmed their rejection to the proposal of bin Omar to move the dialogue outside Yemen, saying that this attempt would fail negotiations. Houthis took control of the Yemeni capital Sanaa, last September. They put the legitimate president Abd Rabbu Mansour Hadi and his prime minister under house arrest late January. He was but they allowed in February to move to Aden, where he created a new capital.