ZURICH (Reuters) - Estimates that Swiss bank UBS will require another $15 billion to $25 billion in capital under government proposals aimed at making the banking sector more robust are about right, Switzerland's finance minister was quoted as saying on Tuesday.

"That's right, those orders of magnitude are plausible," Swiss Finance Minister Karin Keller-Sutter told the Tages-Anzeiger newspaper.

Keller-Sutter was speaking after the Swiss government last week set out proposals to tighten regulation for banks deemed "too big to fail", particularly UBS, which said the lender would face more stringent capital requirements in future.

The government proposals, which must still undergo a long legislative process, did not state how much more capital UBS would need, but sparked calculations from analysts encompassing estimates from $15 billion up to $25 billion, the paper noted.

Tages-Anzeiger said Keller-Sutter was responding to a question about sums in that range, but that she did not indicate at which end of the spectrum she was leaning towards.