Egypt's Foreign Ministry summoned the British ambassador to Cairo on Sunday to complain about comments he made after a judge sentenced three Al-Jazeera English journalists to three years in prison for reporting "false news."
The ministry said in a statement that John Casson's comments were "unacceptable interference" in the country's judiciary" and "incompatible with diplomatic norms and practices."
The court sentenced the three journalists on Saturday, sparking international outcry over the long-running case and highlighting authorities' crackdown on free speech in the country.
Speaking to television cameras in Arabic after the verdict, Casson said he was "shocked and concerned by the sentences," in a case that is of "profound interest to Egyptians because it has become a symbol of the basis for stability in the new Egypt."
"I am concerned that today's ruling will undermine confidence in the basis of Egypt's stability, both in Egypt and abroad," he said.
Several other foreign diplomats at the trial also condemned the verdict, but Casson may have been the only one to speak in Arabic.
The United States, the European Union, the United Nations and a string of human rights advocacy groups and press freedom organisations also sharply criticised it.
Casson's comments were posted on the British Embassy's Facebook page and met with a wave of negative reaction in Arabic and English. Casson also posted similar comments on Twitter, where he is one of the most widely-followed Western diplomats in Egypt with nearly 28,000 followers.
The British Embassy said Casson met Hisham Seif al-Din, chief of staff to Foreign Minister Sameh Shoukry, at the ministry's request on Sunday.
"Ambassador Casson explained the UK position on yesterday's court ruling set out in statements in London and Cairo yesterday," it said in a statement, adding that he would transmit the Egyptian side's concerns to government ministers in London.
The long-running trial of Canadian Mohammed Fahmy, Australian Peter Greste and Egyptian Baher Mohammed had embroiled their work into the wider political conflict between Egypt and Qatar, where Al-Jazeera is based, following the 2013 military ouster of Islamist President Mohammed Morsi.
Evidence presented at the trial ventured into the absurd, including music videos and footage of animals, which defence lawyers and even the judge dismissed as irrelevant. Third party observers say no evidence proved the charges, and critics described it as politically motivated.
Besides the "false news" charge, Judge Hassan Farid said in his ruling that he sentenced the men because they had not registered with the country's journalist syndicate, brought in equipment without security officials' approval and used central Cairo's Marriott hotel as a broadcasting point without permission.
The men are now seeking a pardon from al-Sissi, who has personally expressed regret over the long-running trial and the damage it has done to Egypt's international reputation. They will also appeal once the full verdict is release in the next 30 days.