Kerry and Lavrov sit together during a photo opportunity prior to a meeting, in GenevaBy means of Justyna Pawlak and Fredrik Dahl GENEVA (Reuters) – Foreign ministers from Iran and six world powers laboured on Saturday to beat remaining difficulties and clinch a step forward deal aimed at allaying Western suspicions over Tehran's atomic ambitions. With the perimeters edging closer, U.S. Secretary of State John Kerry and foreign ministers of the five other nations joined the talks with Iran as they entered an unscheduled fourth day. The demand that Iran cease or gradual development of a reactor that would yield doable bomb subject matter gave the impression to be the main outstanding problem keeping up an agreement. British Overseas Minister William Hague and Germany's Guido Westerwelle each counseled that a deal was now not yet assured and that there was work still to do.