HMRC Treatment of an HSA

Does anyone know how HMRC would look upon the interest earned from within an HSA? Those of you that may have one will know that the IRS allows the interest to be exempt from tax, (no 1099). I wonder if this would be treated the same by HMRC; or indeed the interest income would require reporting on SA100?

There is nothing about HSAs in the DTA as far as I know so I would expect it to be treated like regular interest, in the same way as interest in an ISA is taxable in the USA but not in the UK.

IRAs and SIPPs earnings are tax deferred in both countries as per the DTA.

However, I don’t have an HSA and am not a tax expert so may well be wrong. I’ll be interested in seeing the responses.