President Ali Abdullah Saleh refuses to sign the accord for him to step down with immunity, and a regional council says it is ceasing efforts for a deal. Saleh backers besiege an embassy where envoys had gathered to witness the signing.Hundreds of armed supporters of Yemeni President Ali Abdullah Saleh trapped Western and gulf diplomats inside an embassy in the capital for hours Sunday to prevent them from brokering a deal for the longtime leader to step down within a month.