ZURICH (Reuters) - UBS could take years to feel the bite of new regulations after the Swiss government set out plans aimed at keeping the "monster bank" in line that were light on detail and heralded a tortuous political process to enshrine them in law.

Shares in the Zurich-based lender took a knock on Wednesday after the finance ministry said its "too big to fail" recommendations envisaged tougher capital requirements for UBS and other systemically important banks following the rescue of its stricken rival Credit Suisse in 2023.

But the government left open the precise impact it expected from the plan, and analysts said there was little likely to cause UBS great alarm in the pledges to strengthen the market watchdog FINMA, monitor excessive pay and improve backstops.

"The measures proposed by the Federal Council are not enough to finally regulate the banking sector effectively," said Cedric Wermuth, co-leader of the centre-left Social Democrats (SP), the second-biggest party in the Swiss parliament.

"The decision not to introduce stricter capital adequacy criteria is completely negligent and makes a mockery of taxpayers who will have to foot the bill," he added.

Switzerland said that capital demands could be adjusted to reflect exposure to international subsidiaries, as well as lenders' governance, complexity and profitability, without setting specific thresholds.

The government said it was "difficult to reach a final judgement on the exact impact" of its mooted higher capital requirements, but argued Swiss banking would benefit.

"The Federal Council is convinced that the report presented today points the way to a significant improvement," Finance Minister Karin Keller-Sutter told a press conference.

Still, a person familiar with UBS's thinking said the bank was "relieved" by the plan set out and hoped to lobby for less stringent terms during the unfolding political process.

UBS declined to comment.

A person familiar with the government's thinking said legislative changes would not be implemented before 2026 and the back and forth of politics in Switzerland meant that whatever finally passed might not have any effect on UBS until later.

The measures were not intended to be a major shake-up, but a series of steps aimed at putting more safeguards in place to reduce risk in the banking sector, the person said.

The government said it wants to present two packages for implementation in the first half of 2025: one with changes at ordinance level which can be approved by the cabinet, and then more far-reaching draft legislation for parliament.

COMPROMISE

Swiss authorities orchestrated the takeover of Credit Suisse last year, allowing UBS to buy its competitor for 3 billion Swiss francs ($3.3 billion) and creating what critics dubbed a "monster bank" that could capsize the economy if it unravelled.

The sum was a fraction of what Credit Suisse had recently been worth and triggered a subsequent 60% rally in UBS stock.

The supercharged lender now has a balance sheet of around $1.7 trillion, twice the size of the Swiss economy.

Peter V Kunz, a regulatory expert at the University of Bern, described the proposals as a typically Swiss compromise.

"Between the lines I read: 'Let's cross (our) fingers and hope nothing happens with UBS'," he said.

Effective measures would need to be international, he said, noting: "Switzerland cannot do everything on its own."

Analysts say that tougher capital requirements could constrain returns for investors even as details remain vague.

"Much more detail is needed to be definitive," said Thomas Hallett, analyst at KBW.

The uncertainty carries some risk.

A top 10 shareholder told Reuters in January that if UBS wants to remain a Swiss bank, resolving the debate around regulation in its home country is crucial.

Watchdog FINMA and the central bank need to be comfortable with its business model, otherwise there could be friction over the risks that a bank of its size poses, the shareholder added.

The Swiss Bankers Association said the plan threatened to usher in "a wave of regulation that would impose a massive burden on banks and the economy as a whole."

Adriel Jost, a fellow at the Institute for Swiss Economic Policy, said the proposals showed "subsidies" for banks remained in place.

"This will cost Switzerland dearly in the next crisis, be it through the provision of emergency liquidity, a takeover of bad assets, refinancing or temporary nationalization," he said.

"It is a bold bet that slightly increased supervision in advance can change this."

($1 = 0.9122 Swiss francs)