Official says 5 prisoners sought by the US in a swap with Iran have flown out of Tehran

Five prisoners sought by the U.S. in a swap with Iran flew out of Tehran on Monday, an official said.

Flight-tracking data analyzed by the AP showed a Qatar Airways flight take off at Tehran’s Mehrabad International Airport, which has been used for exchanges in the past. Iranian state media soon after said the flight had left Tehran.

The official spoke to The Associated Press on condition of anonymity because the exchange was still in process.

Earlier, officials said that the exchange would take place after nearly $6 billion in once-frozen Iranian assets reached Qatar, a key element of the planned swap.

Despite the deal, tensions are almost certain to remain high between the U.S. and Iran, which are locked in various disputes, including over Tehran's nuclear program. Iran says the program is peaceful, but it now enriches uranium closer than ever to weapons-grade levels.