A 35-year-old Filipino drug trafficker was executed in China on Thursday after repeated pleas by the Philippine government for mercy were rejected, authorities said.

The man was given a lethal injection near the southern Chinese city of Guilin after briefly being allowed to meet with some family members and a Filipino Roman Catholic priest, Vice President Jejomar Binay said.

"The subject was very calm but sad," Binay told a nationally televised news conference, informing the public of the execution even though Chinese authorities refused to confirm the killing.

Binay, who acts as the Philippines' unofficial envoy for Filipinos in trouble overseas, had asked to visit China last week to make a direct appeal to Chinese leaders for mercy, but authorities in Beijing refused his request.

President Benigno Aquino then wrote a letter to his Chinese counterpart, Hu Jintao, asking the sentence to be commuted to life in prison, but was bluntly told in reply that the court's decision was final.

Thursday's execution brought to four the number of Filipinos put to death in China this year for drug trafficking.

The execution of three drug mules in March triggered widespread condemnation in the Catholic Philippines, where capital punishment was abolished in 2006.

However initial reaction to Thursday's execution was relatively muted, with presidential spokesman Edwin Lacierda emphasising that Filipinos needed to resist drug dealers' huge offers of cash to transport narcotics.

"We've always been telling the public and those who work abroad not to be drug mules," he told reporters.

The Philippines has more than 200 people languishing in Chinese jails on drugs related charges, although there are no more left on death row, according to the government.

They are part of what authorities have said is a growing trend of poor Filipinos being targeted by international drug syndicates to transport their merchandise around the world.

About nine million Filipinos work abroad, roughly a tenth of the Philippines' population, and the drug trafficking networks have particularly targeted the overseas diaspora.

Binay said the Filipino executed on Thursday, whose name was not released, was travelling to China as a tourist when he was arrested at a Chinese airport in 2008.

Chinese authorities said he was trying to smuggle in about 1.5 kilogrammes (three pounds, five ounces) of heroin from Malaysia.

In Beijing, Chinese foreign ministry spokesman Hong Lei refused to confirm to reporters on Thursday that the execution had taken place, although he insisted that the man had been treated fairly.

"The Chinese side handled this case in accordance with the law and guaranteed the defendant's litigation rights and interests, and has fulfilled relevant obligations in accordance with international conventions," Hong said.

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