UBS Group AG is mulling a takeover of its embattled Swiss rival Credit Suisse, other sources told Reuters on Saturday, amid a crisis of confidence in the bank that risks destabilizing the global financial system.

Spokespeople at the Treasury and the UK finance ministry did not immediately respond to a request for comment. A spokesperson for the Bank of England's Prudential Regulation Authority, which oversees lenders, declined to comment.

The UK has been a key market for the Swiss lender. Credit Suisse's UK entity, Credit Suisse International, has $60 billion of risk weighted assets, according to the company's latest filings.

The bank also has $44.6 billion of risk weighted assets in its US unit.

(Reporting by Sinead Cruise, additional reporting by Stefania Spezzati; Writing by Elisa Martinuzzi; Editing by Deepa Babington)