Tax on UK property rental

I am a Spanish tax resident ( Uk citizen) and pay tax to HMRC on income from a property I rent in the UK.  I have been advised that I must also pay tax on this income on Spain; the Spanish tax would be lower as 60% of the profit would not be liable for tax. However, surely I should not pay tax on the same income in both countries? If I do have to pay HMRC and the Hacienda, can I claim any relief via the Double Taxation treaty? I have received conflicting information on this subject and hope that so,some will be able to clarify the situation for me. Thank you.

You have to declare the rental income in Spain but you also declare the amount of tax you've paid in UK.

The Spainsih tax man then deducts the tax you've paid in UK from the tax due in Spain. As you are renting your propety long term you get 60% of the rental income as a deduction in Spain so I doubt you'll end up paying any tax on it in Spain as well.