BRUSSELS — A European official says the European Union’s finance chiefs are close to agreeing upon new rules that would force banks to raise just over $140 billion in new capital to be able to sustain worsening market turmoil.

The official said today that EU leaders are expected to sign off on the new guideline for the continent’s biggest banks at a summit on Sunday.

Strengthening Europe’s banks is seen as a key precondition to cutting Greece’s massive debt and finally getting a grip on Europe’s worsening debt crisis.