(CNN) -- The British government condemned China's execution of a British national Tuesday on drug smuggling charges. "I ... am appalled and disappointed that our persistent requests for clemency have not been granted," Prime Minister Gordon Brown said. "I am particularly concerned that no mental health assessment was undertaken." Akmal Shaikh was convicted of carrying up to 4 kilograms (8.8 pounds) of heroin at the Urumqi Airport in September 2007. According to Chinese law, 50 grams (1.76 ounces) is the threshold for the death penalty. China defended the execution in a statement issued by the Chinese Embassy in London. "Drug trafficking is a grave crime worldwide," the statement said. "The concerns of the British side have been duly noted and taken into consideration by the Chinese judicial authorities in the legal process, and Mr. Shaikh's rights and interests under Chinese law are properly respected and guaranteed."
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China defended the execution in a statement issued by the Chinese Embassy in London
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Akmal Shaikh's supporters said he was mentally ill and officials did not take that into account when trying him
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British government had asked China not to execute Shaikh but China says it has followed law
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Family: "We are deeply saddened, stunned and disappointed"
"I made clear that the execution of Mr. Shaikh was totally unacceptable and that China had failed in its basic human rights responsibilities in this case, in particular that @placeholder's court had not considered the representations made about Mr. Shaikh's mental condition."