The central bank says Spain's recession-stricken economy has slumped further in the second quarter and will likely post a sharper contraction than the 0.3 percent of the first three months.

The bank's June report said drops in consumer demand, car sales and industrial production "indicate activity has continued to diminish at a greater rhythm."

Official second-quarter GDP figures are due to be published in July.

Spain, with a 24.4 percent unemployment rate, has agreed to seek a rescue package for its troubled banks but is battling to convince investors it will not need a sovereign bailout like Greece, Ireland and Portugal.

The interest rate for Spain's benchmark 10-year bonds — an indicator of investor wariness — was at 6.83 percent Wednesday, a rate considered unsustainable over the long term.