Iran has warned that it will respond forcefully if Britain makes "new mistakes", while London has warned of Tehran slipping into "more political and economic isolation."
The Iranian warning came after Tehran detained British Ambassador Rob MacAir for a short time after accusing him of participating in an "illegal gathering", in reference to the demonstrations that took place after Tehran agreed to bring down the Ukrainian plane by mistake and killed 176 people, most of them foreigners.
The Iranian Foreign Ministry statement said that the British ambassador's participation in a demonstration in Tehran is a clear interference in Iran's internal affairs, explaining that the ambassador's presence raises doubts and contradicts diplomatic norms.
On the other hand, British Foreign Secretary Dominic Rapp warned the Iranian regime against slipping into further political and economic isolation.
"The arrest of the ambassador is a flagrant violation of international law," Rapp told the British House of Commons (Parliament), adding that the regime in Tehran is at a crossroads.
On Monday, the British Foreign Office summoned the Iranian ambassador in London to express its "strong objections" to the arrest of the British ambassador.
A spokesman for the British Prime Minister said the arrest was "an unacceptable violation of the Vienna agreement," adding that the UK had asked Ambassador Hamid Baidi Nejad guarantees that it would not happen again.
Ambassador Rob MacAir said that he went to the declared gathering in honor of the victims of the crash of the Ukrainian civil plane, which was hit "error" by an Iranian missile.
British media reported that the Iranian authorities arrested the British ambassador to Tehran on Saturday and then released him, against the background of photographing the demonstrations taking place in the Iranian capital, and on the same day, a gathering in Tehran, during a memorial service for the victims of the Ukrainian plane that crashed a few days ago in Iran, turned into a demonstration Anti-regime in the country.