Britain's foreign ministry was "urgently investigating" an incident on a vessel off the UAE coast.
Iranian emergency services said the diplomat's body was found by a gardener.
Iran said the person who caused an electricity outage in one of the production halls at the underground uranium enrichment plant had been identified.
The problem involved the electrical distribution grid of the Natanz site.
Biden's refusal to lift sanctions has been met by a show of unity from both sides of Iran's political divide.
Sahar Tabar became well-known for her extremely gaunt appearance on social media.
The SIS raided the Iranian embassy in Wellington in the late 1980s and early 1990s.
"We will reward anyone who brings us [Trump]'s head with that amount."
