Aug. 17 (UPI) — Iran has accused Qatar of holding three of its pilots for half a year in violation of international law, heightening tensions between the two nations and threatening to expand the war in the Middle East, despite Doha claiming not to have the pilots.

“Qatar’s government has exhausted its opportunity to delay and toy with the fate of three heroic Iranian pilots,” Maj. Gen. Ali Abdullahi, the newly appointed chief of staff of Iran’s Armed Forces, said in a statement Sunday.

“They must be released immediately and unconditionally and returned to the homeland.”

Four Iranian pilots in two SU-24s were shot down over Qatari airspace March 2, as Iran was attacking Al Udeid Air Base in response to joint Israeli-U.S. attacks on Iran days earlier that ignited the ongoing war. A Qatari foreign ministry spokesperson said that a search had been launched for their crews, but it was never stated that they had been found. Iran later announced that one of the four pilots had died in the attack.

On Saturday, Brig. Gen. Mohammad Bagherzadeh, head of the Iranian military’s committee for missing personnel, identified the remaining three pilots in a letter to the International Red Cross that accuses Qatar of violating articles of the Geneva Convention concerning the treatment of prisoners of war, the state-run Islamic Republic News Agency reported.

Bagherzadeh accused Doha of denying the pilots contact with their families and Iranian authorities, citing Articles 70 and 78 of the Third Geneva Convention that states POWs have the right to submit complaints and requests to representatives who visit their place of captivity or to hold discussions and negotiations.

The letter urged the ICRC to address the situation.

“Qatar must know that Iran will not retreat from its proud pilot sons. The path for the presence of the expert team of the Islamic Republic of Iran must be facilitated as soon as possible,” Brig. Gen. Seyed Majid Mousavi, commander of the Islamic Revolutionary Guard Corps, said Sunday in a statement.

“Continuing this trend will not be cost-free for Qatar, and any delay or obstruction will place a heavy responsibility on their shoulders.”

Qatar has denied the accusations. Majed Al Ansari, spokesperson for Qatar’s Ministry of Foreign Affairs, said Qatar was not holding any Iranian pilots and had handed over the remains of one Iranian pilot that its search teams had found.

Qatar invited Iranian officials in April to visit Qatar and be briefed on the search-and-rescue operations, “but the Iranian side has yet to respond to the invitation,” he said in a statement Sunday.