Iranian authorities warned Nato member Bulgaria last month not to let the US use its airports for planes participating in military operations in Iran, the foreign ministry has said, Reuters reports.

Earlier today, Stanislav Balabanov, a deputy with the “There is Such People” party, showed a note from March 18 in which the Iranian government protested against US military refuelling planes parked at Bulgaria’s Vasil Levski airport.

In the note, Iran said it “reserves the right to take all necessary measures to protect its sovereignty, security and national interests in accordance with international law”.

Later, Deputy Foreign Minister Marin Raikov confirmed the note and said: “Bulgaria is not at war.”

“No combat aircraft are being loaded over Bulgaria to participate in military operations,” he told reporters. “We maintain intact diplomatic relations with the Iranian side.”