The Islamic Republic President, Hassan Rouhani, has offered his congratulations to the new UK Prime Minister, Boris Johnson, expressing hope that bilateral relations will further develop during his tenure.

In the message published on Sunday, July 28, Rouhani said, "I hope that Your Excellency's familiarity with relations between Iran and the United Kingdom, and your only visit to Tehran will greatly contribute to removing the existing obstacles on the path of development of relations between the two countries."

Rouhani was referring to Boris Johnson's December 2017 visit to Iran. Then Foreign Secretary, Johnson tried to address several disputes between Tehran and London, including the case of a 40-year old Iranian-British mother, Nazanin Zaghari-Ratcliffe, held in custody in Tehran's notorious prison, Evin.

Mrs. Ratcliffe has been held in custody since April 3, 2016 on arbitrary charges after visiting her family in Iran. In early September 2016, she was sentenced to five years' imprisonment allegedly for "---plotting to topple the Islamic Republic regime."

Furthermore, Johnson also hoped to tackle the problem of repaying a 400 million pound (approximately $495 million) sum claimed by Iran, perhaps helping the release of Ratcliffe.

The initial dispute goes back to a 1970s defense deal between the Royal Iranian Defense Ministry and International Military Services (IMS), a venture owned by the British MoD. IMS agreed in 1971 to sell the king of Iran, Shah Mohammad Reza Pahlavi, more than 1,500 Chieftain tanks and armored vehicles. Tehran canceled the contracts in February 1979 after the pro-Western Shah was toppled by revolution. Having already paid for the undelivered tanks, Tehran has demanded its money back.

In the meantime, tensions between London and Tehran have taken a turn for the worse this month. Iran seized a British-flagged tanker in the Strait of Hormuz on July 19, two weeks after the British forces captured an Iranian oil tanker near Gibraltar, accusing it of violating sanctions on Syria.