BENGHAZI, Aug 26 (Reuters) - Oilfields in eastern Libya that account for almost all the country's production will be closed and production and exports halted, the eastern-based administration said on Monday, after a flare-up in tension over the leadership of the central bank. There was no confirmation from the country's internationally recognised government in Tripoli or from the National Oil Corp (NOC), which controls the country's oil resources. NOC subsidiary Waha Oil Company, however, said it planned to gradually reduce output and warned of a complete halt to Libya's production, citing unspecified "protests and pressures". Another subsidiary Sirte Oil Company...