LONDON — Downing Street has firmly denied reports that Britain's National Security Adviser Jonathan Powell participated in crucial US-Iran nuclear negotiations before coordinated strikes against Tehran, contradicting earlier media accounts of last-minute diplomatic engagement.

The Guardian newspaper reported Tuesday that Powell had attended final talks between Washington and Tehran, suggesting Iran's nuclear concessions were substantial enough to warrant delaying military action. However, a spokesperson for Prime Minister Keir Starmer rejected these claims Wednesday, stating categorically that Powell was not involved in the concluding negotiations.

"The National Security Adviser did not participate in the final round of talks between the United States and Iran," the spokesperson told reporters at the weekly briefing. "While we support diplomatic engagement, Britain was not directly involved in these particular discussions." The clarification comes as parliamentary opposition members demand transparency about the government's knowledge of diplomatic initiatives before the strikes.

Diplomatic sources in Vienna suggest multiple communication channels remained active between Washington and Tehran until hours before the operation commenced. "There were various back-channel efforts to find a compromise on uranium enrichment levels," said Dr. Hassan Ahmadian, a Middle East analyst at Tehran University. "Whether these represented genuine progress or tactical delays remains unclear." The strikes targeted Iranian nuclear facilities and missile production sites in response to escalating regional tensions.