I have a property in the UK on which I pay a mortgage, I rent this out at a loss overall as I live here permanently. Am I able to claim deductions on the interest paid against this property if the loan is held in a uk bank?

If you are a U.S. citizen or resident, you must report this rent income on schedule E (Form 1040). You can deduct your expenses.
If you have a net loss, you can claim this on your tax return. Read: Your U.S. Tax Return: U.S. Citizen or Resident with Foreign Income

There IS an income limitation which MAY prevent you from claiming the rental loss.

It comes into play when your income hits $125,000.

Hello, I hope it is OK if I tag onto this post and ask a related question...

If the house in the UK is sold, and capital gains taxes paid to that Government, would one be liable to pay the US additional capital taxes?

Thank you!

You may or may not have additional taxes. With your tax return, you will do Form 1116 foreign tax credit to get credit for taxes paid in UK.