“The U.K. is completely opposed to the use of the death penalty in all circumstances,” Mr. Miliband said in a statement. “However I also deeply regret the fact that our specific concerns about the individual in this case were not taken into consideration, despite repeated calls by the prime minister, ministerial colleagues and me.”

Mr. Shaikh’s daughter, Leilla Horsnell, was quoted by the BBC as saying she was “shocked and disappointed that the execution went ahead with no regards to my dad’s mental health problems, and I struggle to understand how this is justice.”

British officials had pressed the Chinese courts to consider Mr. Shaikh’s history of mental disturbance and to allow an independent evaluation of his mental state. But China’s highest court, the Supreme People’s Court, rejected a last-minute appeal from the family and British officials and allowed the execution to go ahead as scheduled.

Two of Mr. Shaikh’s cousins, Soohail and Nasir Shaikh, who traveled to China to visit him in prison and make a last-minute plea for clemency, said they were “astonished at suggestions that Akmal himself should have provided evidence of his own fragile state of mind,” according to the BBC.

China defended its handling of the case at a regularly scheduled press conference at the Foreign Ministry in Beijing saying that criticisms were. “groundless,” and “China expressed its resolute opposition” to them, said Jiang Yu, a spokeswoman for the Foreign Ministry, according to the English-language report on Xinhua.