US and Iranian officials held indirect talks in Oman last month with Omani officials shuttling between their separate rooms to deliver messages, three sources briefed on the issue told Axios, Report informs.

The “proximity talks,” which haven’t been previously reported, represent the first known indirect engagement between the US and Iran in this way in several months. They took place amid growing concerns in the White House about Iran’s nuclear advances.

White House Middle East coordinator Brett McGurk traveled to Oman secretly on May 8 for talks with Omani officials on possible diplomatic outreach to Iran regarding its nuclear program, as Axios reported last week. According to the three sources briefed on the issue, an Iranian delegation also arrived in Oman at the same time. Iran’s top nuclear negotiator Ali Bagheri Kan was part of the delegation, one of the sources said. McGurk and the Iranian officials didn’t meet, according to the sources. The two sides were in separate locations with Omani officials going between them and passing messages.