Akmal Shaikh was arrested in 2007
A British man convicted of drug smuggling in China has been executed, the Foreign Office has confirmed.
Akmal Shaikh, 53, of London, had denied any wrongdoing and his family said he was mentally ill.
The execution took place despite repeated calls from his family and the British government for clemency.
British Prime Minister Gordon Brown said he was "appalled and disappointed", and condemned the execution "in the strongest terms".
Mr Shaikh is the first EU national to be executed in China in 50 years.
In a statement, Mr Brown said: "I am appalled and disappointed that our persistent requests for clemency have not been granted.
"I am particularly concerned that no mental health assessment was undertaken.
"At this time our thoughts are with Mr Shaikh's family and friends and I send them our sincere condolences."
Foreign Secretary David Miliband also condemned the execution.
He said the UK was opposed to the use of the death penalty in all circumstances, but also "deeply regretted" that his specific concerns in this case - over mental health issues and interpretation during the trial - had been ignored.
CHINA DEATH PENALTY
China executed 1,718 people in 2008, according to Amnesty International
Last year 72% of the world's total executions took place in China, the charity estimates
It applies to 60 offences, including non-violent crimes such as tax fraud and embezzlement
Those sentenced to death are usually shot, but some provinces are introducing lethal injections
Mr Shaikh has denied all knowledge of the 4kg of heroin found in his possession by police in the north-western city of Urumqi in 2007.
His family said he suffered from bipolar disorder and had displayed "extreme and erratic" behaviour.
His daughter Leilla Hornsell has said her father was approached by drug smugglers in Poland, who convinced him they would make him a pop star in China.
She claims he was then duped by the gang into carrying a suitcase that did not belong to him.