HSBC Holdings Plc might pay a fine of $1.8 billion as part of a settlement with U.S. law-enforcement agencies over money-laundering lapses, Reuters reported citing several people familiar with the matter.

The settlement with Europe's biggest bank - which could be announced as soon as next week - will likely involve HSBC entering into a deferred prosecution agreement with federal prosecutors, said the sources, who spoke on condition of anonymity.

The potential settlement, which has been in the works for months, is emerging as a test case for just how big a signal U.S. prosecutors want to send to try to halt illicit flows of money moving through U.S. banks.

An HSBC spokesman said: "We are cooperating with authorities in ongoing investigations. The nature of discussions is confidential."

HSBC said on Nov 5 that it set aside $1.5 billion to cover a potential fine for breaching anti-money laundering controls in Mexico and other violations, although Chief Executive Stuart Gulliver said the cost could be "significantly higher.

In regulatory filings, HSBC has said it could face criminal charges. But similar U.S. investigations have culminated in deferred prosecution deals, where law-enforcement agencies delay or forgo prosecuting a company if it admits wrongdoing, pays a fine and agrees to clean up its compliance systems. If the company missteps again, the Justice Department could prosecute.