Iran warned Bulgaria on July 27 over its decision to host US military refuelling aircraft, saying Bulgarian officials would bear responsibility for allowing their territory to be used in support of US operations, as Sofia sought to reassure the public that there was no immediate security threat.

The latest statement, posted by Iran's embassy in Sofia and attributed to foreign ministry spokesperson Esmaeil Baghaei, was the third warning issued by Tehran since Bulgaria approved the deployment of US aircraft at Bezmer Air Base earlier this month.

"Decision-makers in Bulgaria must bear responsibility for the dangerous decision to deploy a US aerial refuelling aircraft to their military bases," the statement said, Euronews reported,

Iran said it was aware that Bulgaria had previously allowed US aircraft to operate from its territory in support of US military actions against Iran.

"The Bulgarian people know well that the Iranian people have never had any problems with Bulgaria. For decades, our relations with Bulgaria have been based on mutual respect," the statement added.

The warning came days after US President Donald Trump publicly thanked Bulgarian Prime Minister Rumen Radev on his Truth Social platform for supporting the deployment of US military aircraft despite Iranian objections.

Bulgaria's National Assembly voted on July 22 to authorise the deployment of up to eight US Air Force KC-135 aerial refuelling aircraft and as many as 250 US military personnel at Bezmer Air Base, about 260 km (160 miles) southeast of Sofia. The deployment, approved by 136 lawmakers with 13 voting against and two abstaining, is scheduled to run from July 24 until October 1 under a bilateral defence cooperation agreement with the United States.

The aircraft are intended to support US military operations in the Middle East. Defence Minister Dimitar Stoyanov has said they are expected to arrive this week.

Iran first objected to the deployment on July 21, warning that facilitating US military operations against Tehran would make Bulgaria complicit in what it described as "aggression and war crimes." Tehran urged Sofia to reject the request and avoid becoming "an accomplice of aggressors and lawbreakers."

Bulgarian officials have sought to ease concerns over the escalating rhetoric.

Deputy Parliament Speaker Ivan Angelov said Sofia had been in contact with Tehran to stress that Bulgaria was not a party to the conflict and that the deployment did not change its position.

Representatives of Bulgaria's security services told a meeting chaired by Prime Minister Rumen Radev on July 27 that there was no direct threat to the country's security, according to a government statement.

The government said Bulgarian authorities remained in close contact with NATO allies and regional partners to monitor developments in the Middle East and Ukraine and receive timely warning of any escalation.

It added that security had been strengthened at Bezmer Air Base and measures taken to protect Bulgaria's airspace and public safety, Mediapool reported.

A NATO spokesperson said last week that the alliance would defend Bulgaria against any retaliation linked to the deployment, following parliamentary approval of the US aircraft.

The decision places the European Union and NATO member state within the logistics network supporting US operations in the Middle East at a time when some allies have been reluctant to provide similar basing support.