French President Emmanuel Macron’s top diplomatic advisor traveled to Iran on Wednesday to hold talks with local officials as part of European efforts to reduce tensions in the Gulf region, a presidency official said.

“The diplomatic advisor did indeed travel to Iran on June 19...to hold high-level talks with the objective of contributing to a de-escalation of tensions in the region,” the official said, confirming information from two diplomatic sources.

The diplomat, Emmanuel Bonne, has been based in Iran in the past and is a Middle East expert.

The United States sought on Wednesday to bolster its case for isolating Iran over its nuclear and regional activities by displaying limpet mine fragments it said came from a damaged oil tanker and saying the ordinance looked Iranian in origin.

Iran has denied involvement in explosive strikes on two tankers in the Gulf of Oman last week and four tankers off the United Arab Emirates on May 12, both near the Strait of Hormuz, a major conduit for global oil supplies.