British intelligence agency GCHQ "would not confirm of deny the existence of the Squeaky Dolphin" monitoring programme, according to NBC News.
A spokesperson for the agency said GCHQ's work was "carried out in accordance with a strict legal and policy framework”.
This "ensure[s] that our activities are authorised, necessary and proportionate, and that there is rigorous oversight, including from the Secretary of State, the Interception and Intelligence Services Commissioners and the Parliamentary Intelligence and Security Committee", the spokesperson added.
More top news
Regina Murmura was shot dead in front of her husband of 50 years, who tried to get her to hospital but it was too late.
Downpours across southern Britain will journey northwards to affect many places before the end of the day - some intense and thundery.
European court says US-EU treaty allowing transfer of personal data by US companies is invalid due to privacy fears.