Swiss lawmakers have passed a tax proposal seen as key to settling a U.S. probe into Swiss banks with hidden offshore accounts.

The proposal, which clarifies how Switzerland would hand over data on Americans suspected of dodging taxes at home, seeks to backstop an expected deal over U.S. probes into 11 banks including Credit Suisse and Julius Baer, likely to comprise a data handover and fine payment.

Switzerland's lower house on Monday passed the proposal by 110 votes to 56 votes, sealing an initial backing taken last week. Switzerland's upper house passed the plan in December.

Specifically, the plan would allow Switzerland to hand over data on suspected tax evaders, even if U.S. tax authorities cannot identify alleged offenders by name or bank account.

The move represented a weakening of Switzerland's long-cherished secrecy laws, which have underpinned its finance industry on which the economy relies heavily.

Provided a 100-day waiting period without a call for a referendum, attention is likely to shift to the U.S.-Swiss talks, which is meant to sweep Swiss bank accounts clean of offenders and make good on past transgressions.

According to a source familiar with the matter, Swiss and U.S. talks are continuing, with sticking points still in the deal's details.

Switzerland's SIF, negotiating the deal for the Swiss government, would not comment on parliament's decision.

(Reporting by Katharina Bart; editing by Dan Lalor)