National City, the US bank that has been among the hardest hit by the subprime crisis, is trying to reduce its exposure to the riskiest category of home loans by offering customers cash to close their untapped home equity lines.

If the scheme is successful, analysts say other banks could follow suit, choosing to spend money now to avoid taking on more exposure to the US housing slump. Lenders such as National City have tightened their lending standards and reduced lending volumes sharply, but portfolio exposures could still grow as a result of so-called "open-ended" home equity lines that are committed but as yet undrawn.