*BoE's Posen: Need Further Monetary Action To Sustain, Promote Recovery

*Pound Slides Against Majors; Hits 4-day Low Of 0.8537 Against Euro

Oman C.bank Head Says No Debt Issues Planned at Moment

Mexico's Peso Gains 0.68 Pct to 12.5022 Per Dollar After Us Home Prices Data

U.s. Treasury Prices Turn Positive After Case-Shiller Home Price Index