China plans to execute a British man convicted of drug smuggling before the end of the year, officials said Monday, ignoring a personal appeal from Prime Minister Gordon Brown to spare the man's life.

Britain's Foreign Office said that Chinese authorities have told them they plan to execute Akmal Shaikh, a 53-year-old man whose supporters say has mental health problems and was duped into carrying drugs into China, on Dec. 29.

"We are alarmed and deeply concerned at this news," the Foreign Office said in a statement. "We will be using the next few days to renew and intensify our appeal to the Chinese authorities for clemency."

Human Rights group Reprieve said that Shaikh's appeal had been rejected by the People's Supreme Court of China, exhausting his legal options.

"Akmal's last chance appears to be clemency," Reprieve said in a statement, appealing to Chinese President Hu Jintao to grant Shaikh a pardon.

"It is impossible to imagine what Akmal's family are going through this holiday season," Reprieve Director Clive Stafford Smith said. "This is no time for pride — they beg the Chinese authorities to show compassion and take Akmal's mental health problems into account."

Shaikh, a small business owner from north London, was sentenced to death in October 2008 after being convicted of taking a suitcase containing almost 9 pounds (4 kilograms) of heroin into the far western Chinese city of Urumqi.

Family members say Shaikh has a lifelong history of unbalanced behavior, and British officials have expressed concerns over his mental health. Reprieve claims that Shaikh was lured to China by men who promised to help him launch a career in pop music and has cited a preliminary medical report that states that Shaikh's actions "were most likely influenced by some form of delusional psychosis."

The Foreign Office accused Chinese officials of not taking Shaikh's mental health concerns into account — despite repeated requests from his lawyers, the prime minister and a host of British and European officials.

A call seeking comment from China's Foreign Ministry was not immediately returned late Monday, but China has defended the integrity of the case.

At a media briefing in October, Foreign Ministry spokesman Ma Zhaoxu said there was no proof that Shaikh had mental health problems.