Bank Interest Income on Foreign Pension Money

Hi, I am not UK citizen and before moving and settling in UK, I used to be an international staff of a UN (United Nations) organization whose employees do not pay tax to their home countries based on agreement of member states in the governing board. I don't know how they do it but the equivalent income tax is considered as annual contribution of the employee's home country to the UN, Thinking of self-employment, I retired early, withdraw all my pensions. The pension money which is in USD is earning some interest in off-shore account of UK bank until I set up a small business. Given that this is foreign pension related to untaxed foreign (international) salary, I believe I should not pay UK tax on the off-shore bank interest income. On top of that, since I am managing my own pension money, it can be considered as a kind of SIPP (Self-Invested Personal Pension) and thus free from UK tax? Your view much appreciated.

Hi Afewerki Mekonnen,
Please refer to: Tax on foreign income.
Thank you.