Rightmove Plc said that asking prices by London home sellers declined in August by the most in a year, as the financial market instability hit demand in Britain's most expensive property market.

The U.K's biggest property website said and emailed report today that asking prices dropped by 3.4% from previous drop of 1.4%. On a national basis, value fell 2.1%, which is the second consecutive monthly decline and the largest since the month of December.

In August national asking prices were down 0.3% from a year earlier to an average of 231,543 pounds ($377,000), Rightmove said.

While values are being supported by record low interest rates, lack of property supply and waning consumer confidence and the potential impact on bank lending from an escalation of Europe's debt crisis may undermine activity further, Rightmove said.